SF 761 
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Copy 1 



VETERINARY SCIENCE ASSOCIATION 
OF AMERICA 



NOTES ON 

VETERINARY ANATOMY 

BY 

\ 

CHARLES J. KORINEK, V. S. 

Graduate of the Ontario Veterinary College, in affiliation with 
the University of Toronto, Canada. Hon. Member of the On- 
tario Veterinary Medical Society. Ex. State Veterinarian for 
Oregon. Ex. President of the Oregon State Veterinary Medical 
Board of Examiners. Author of "The Veterinarian". Princi- 
pal of the Veterinary Science Association of America. Sixteen 
years of Practical Experience as a Veterinary Surgeon. 




PUBLISHED BY THE 

VETERINARY SCIENCE ASSOCIATION 
OF AMERICA 



VETERINARY SCIENCE ASSOCIATION 
OF AMERICA 



NOTES ON 

VETERINARY ANATOMY 

BY 

CHARLES J. KORINEK, V. S. 

Graduate of the Ontario Veterinary College, in affiliation with 
the University of Toronto, Canada. Hon. Member of the On- 
tario Veterinary Medical Society. Ex. State Veterinarian for 
Oregon. Ex. President of the Oregon State Veterinary Medical 
Board of Examiners. Author of "The Veterinarian". Princi- 
pal of the Veterinary Science Association of America. Sixteen 
years of Practical Experience as a Veterinary Surgeon. 




PUBLISHED BY THE 

VETERINARY SCIENCE ASSOCIATION 
OF AMERICA 



^Y 






tl3 



COPYRIGHT 1917 

by the 

VETERINARY SCIENCE ASSOCIATION 

OF AMERICA 






©GiA4r;3712 



22 1917 



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I 



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TABLE OF ILLUSTRATIONS. 



Page 

Plate I. Skeleton of the Horse 7 

Plate II. Muscles of the Horse, superficial layer 29 

Plate III. Muscles of the Horse, deep layer. ... 31 

Plate IV. Digestive and Urinary Organs of the 

Horse 37 

Plate V. Heart and Chief Blood Vessels of the 

Horse 69 

Plate VI. Nervous System of the Horse 73 

Plate VII. Structure of the Horse's Foot 78 



TABLE OF CONTENTS. 



Page 

Chapter I. Osteology, or Structure of the 

Bones 8 

Chapter II. Arthrology, or Study of the Joints 21 

Chapter III. Myology, or Study of the Muscu- 
lar System 28 

Chapter IV. Splanchnology, or Study of the 
Digestive, Respiratory, Urinary 
and Generative Systems 38 

Chapter V. Angiology, or Study of the Blood- 
Voscular System, as the Heart, 
Arteries, Veins, Lymphatic Ves- 
sels and Glands 67 

Chapter VI. Neurology, or Study of the Nerv- 
ous Tissue, as the Brain, Spinal 
Cord and Their Nerves 73 

Chapter VII. Aesthesiology, or the Study of the 
Organs of Special Sense, as the 
Ear, Eye and Organs of Sensa- 
tion, as Skin, Hair, Foot, etc ... 75 

Chapter VIII. Embryology or Development of 

the Foetus 81 



PREFACE 

There are a number of excellent works on Veterinary 
Anatomy, and many of them will amply repay the stu- 
dent for the time taken to master them, but for quick 
reference none seem to contain the wants of the veterin- 
ary practitioner and student for which this humble little 
work is primarily intended. 

It has been my endeavor to briefly describe each 
organ as found in the healthy animal ; its functions, etc., 
in a condensed yet complete form. I am positive that the 
student or veterinary practitioner will find its pages 
highly instructive as well as profitable and interesting. 

In compiling this work a few authorities have been 
consulted and quoted, while it has not been practical to 
give individual credit for the use of ideas and language, 
a general acknowledgement is here made: 

Veterinary Science, Hodgins and Haskett. 
Veterinary Anatomy, Strangeways. 

Charles J. Korinek, V. S. 



DESCRIPTIVE ANATOMY 

Osteology is a term applied to that section of de- 
scriptive anatomy which treats of the bones. Arthrology, 
to the consideration of the joints or modes of union be- 
tween the bones, while by Myology is meant the doctrine 
of the muscular system. Splanchnology treats of the 
viscera, Angiology of the circulatory and absorbent sys- 
tems. Neurology deals with the nervous system. Aes- 
thesiology with the organs of sense ; while JEmhryology, 
as before stated is the consideration of the animal frame 
at periods preceding its birth. 

In this work the various departments are discussed 
in the order here given. The structures which are the 
subject of the first three divisions are sometimes classed 
together as the Organs of Locomotion; for bones form 
the frame work of the body and often act as levers; the 
joints connect the bones, permitting more or less motion 
between them ; while the muscles moA^e the bones, and so 
produce motion of a part of the body — or it ma}^ be 
locomotion, or change of situation in the entire frame. 

In the study of comparative Anatomy the terms 
analogy and hoinology are frequently met with. Al- 
though these words are unfrequently used indiscrim- 
inately, the following differences should be noted. 
Organs are said to be analogous when, through differ- 
ing in structure, they preform the same function; but 
when their functions are different, which, in the broad 
sense, they correspond in structure or form, they are 
said to be homologous. Thus the middle finger of the 
human hand is the homologue of the anterior '(front) 
digit of a horse, because they have the same general 
structure, and relation to the rest of the limb; but as 
the functions they perform are quite dissimilar, they 
cannot be termed analogous. Again, the lungs of a 
mammal are analogous to the gills of a fish, for, though 
they differ widely in structure, position and form, and 



VETERINARY ANATOMY 



are therefore not homologous, their ultimate use is the 
same — each of them being an apparatus in which is car- 
ried on the process of purifying the blood. 



DISSECTION. 

Students must dissect as many animals as possible, 
so as to familiarize themselves with the frame work or 
structure, and the location of the digestive, nervous and 
blood systems, as it will aid materially in the art or pro- 
cess of determining the nature of various diseases. 

During cool weather an animal for dissecting pur- 
poses can be kept for a considerable length of time with- 
out preservatives 

It is well to have a copy of Anatomy at hand when 
dissecting for it will show the location of the various 
organs and explain their functions. 



EXPLANATION OF PLATE I 

Skeleton of the Horse 



1. Skull, or skeleton of the head. 

2. Cervical vertebrae or neok 

bones. 

3. Dorsal vertebrae or back 

bones. 

4. Lumbar vertebrae or loin 

bones. 

5. Sacral vertebrae or rump 

bones. 

6. Coccygeal vertebrae or tail 

bones. 

7. Pelvic or hip bones. 

8. Sternum or breast bone. 

9. Ribs. 

10. Scapula or shoulder blade. 

11. Humerus or shoulder bone. 

12. Radius or bone of the fore- 

arm. 

13. Ulna or bone of the fore-arm. 

14. Carpus or bones of the knee. 

15. Os Melacarpi Magnus, meta- 

carpal, or cannon bone. 

16. Ossa Melacarpi Parva, or 

splint bones. 



17. Proximal Phalanx, os suffra- 

ginis, or large pastern 
bone. 

18. Great Sesamoid Bones. 

19. Medium Phalanx, os coronae, 

or small pastern bone. 

20. Distal Phalanx, os pedis, or 

coffin bone. 

21. Os Naviculare, small sesa- 

moid, or shuttle bone. 
(This bone can be plainly 
seen Plate VII). 

22. Pemer, or thigh bone. 

23. Patella, or stifle bone. 

24. Tibia, or leg bone. 

25. Fibula. (This bone is little 

developed in the horse.) 

26. Tarsus or hock bones. 

27. Metatarsus,, or os metatarsi 

magnus. 

28. Ossa Metatarsi Parva, or 

splint bones of the hind 
leg. 



Names of joints placed according to numbers. 



I. Shoulder Joint. 

II. Elbow Joint. 
III. Carpus or knee joint, 
rv. Fetlock Joint. 

V. Pastern Joint. 



VI. Coffin Joint. 
VII. Hip Joint. 
VIII. Stifle Joint. 
IX. Tarsus or hock joint. 



CHAPTER I. 
OSTEOLOGY. 

Structure of the Bones — Bones are hard, yellow- 
white, insensitive objects, which form the skeleton and 
give attachment to soft structures (muscles, tendons 
and ligaments) ; they are of various sizes, forms and den- 
sities. In the limbs the bones are ordinarily more or less 
long, circular bodies, with expanded ends, effectually 
supporting the body, supplying leverage and attachment 
for soft structures, and forming the basis of all joints. 
Where cavities, such as the cranium, chest, and pelvic, 
enclosing the organs requiring protection and support, 
the bones tend to assume a flat, expanded form. 

Living bone is bluish pink, insensitive, and elastic; 
on exposure to air it becomes diseased and blackened, 
very sensitive and painful; '(the teeth excepted) which 
are harder and of a higher specific gravity than any other 
bone formation. 

Bones are composed of two kinds of substance — 
animal, which makes the bone tough and flexible ; earthy, 
which makes it hard and fragile. In young animals the 
animal matter forms about one-half of the bone sub- 
stance ; in the adult, it diminishes to about a third, while 
in old animals it is still less ; hence the bones of very old 
animals are brittle, more liable to fracture and harder to 
mend. 

Bones in a six-year-old horse contained. Phosphate 
of Lime, 54.37 per cent; Carbonate of Lime, 12.00 per 
cent; Phosphate of Magnesia, 1.83 per cent; Soluble 
Salts, 0.70 per cent, or mineral matter, 68.90 per cent. 
While they contain Cartilage, 27.99 per cent; Fat, 
etc., 3.11 per cent, or animal matter 31.10 per cent. 

In bone tissue there are two modifications of texture, 
the compact and the cancellated. The former — hard, 

8 



OSTEOLOGY 9 

dense, and ivory-like, is always situated externally; the 
latter porous and spongy lies within. 

Although the compact tissue appears uniformly 
dense, and destitute of porositj^ yet, if we transversely 
sectate the shaft of a long bone, and examine it under 
the microscope, by transmitted light, it is found to con- 
tain numerous round openings. These are called Haver- 
sian canals. They transmit bloodvessels, and run in a 
longitudinal or slightly oblique direction, opening on 
either the outer or inner surface of the bone. 

The external (outer) surface of everj^ bone is cov- 
ered by a tough, fibrous, inelastic membrane called peri- 
osteum, which can be seen by examining the bone of an 
animal which has recently died. The only exception to 
this is at the joints where one bone articulates with 
another, and where a tendon or muscle plays over a bone; 
here we find its place taken by articular cartilage. By 
its strength it sometimes retains bones in contact after 
an oblique fracture ; in the young, it is thicker and more 
vascular than in the adult. Blood-vessels which pene- 
trate the periosteum pass directly to the bone ; the outer 
surface of the bone is always studded with numerous 
foramina through which these enter. 

The periosteum owing to its inelasticity, is, when 
inflamed, the seat of intense pain; and should any part 
of it be stripped off, there is everj^ probabilitj^ of the 
denuded bone dying and separating. 

Contents of Bone. — Red marrow is found in the 
extremities or near the ends of bones, white marrow is 
found in the shaft. 

Classes of Bones. — Bones are classed as long, flat, 
and irregular. Long or cylindrical bones are found in 
the limbs or extremities, and serve as levers and pillars 
for traveling and to support the body. Descriptively, a 
long bone is divisible into a center or shaft and two ends 
or extremities. Flat bones are found where visceral 
organs need protection. As the shoulder or scapula and 
ribs, to protect the heart and lungs ; pelvic or hip bones, 



10 VETERINARY ANATOMY 

to protect the rectum and urinary and genital organs; 
also the cranial bones, to protect the vital organ called 
the brain. 'Irregular bones are found in the spinal col- 
umn and in the joints, such as the knee or carpus, hock 
or tarsus, where great strength is required. They usual- 
ly possess many angles and indentations, with surfaces 
for articulation and tendonous attachment, and consist 
of a thin, dense, external (outer) case of compact bone 
enclosing cancellated tissue. In proportion to their size 
they present a much larger extent of articular surface 
and greater mechanical strength than any other class. 

1. Skull^ or skeleton of the head, the most anterior 
(forward) part of the horse's skeleton, articulates with 
the first cervical vertebra (or atlas), from which it is 
suspended by its posterior (or back part) extremity, its 
anterior (forward) extremity being free. Its position 
varies with the attitude of the animal; but in our de- 
scriptions we shall always suppose it to be placed in a 
horizontal position. 

In the young animal the skull is composed of a num- 
ber of bones, all of which, with the exception of the lower 
jaw, the teeth, the bones of the tongue, and ossicles of 
the ear, become united by ossification (growing 
together) in the adult. 

In speaking of the different points of importance in 
connection with the head bones of the horse, and other 
animals, suppose a cross or longitudinal section of the 
head is made. It will be noticed that it is full of cav- 
ities or sinuses. The uses of these are to lighten the 
head and also to warm the air as it passes into the nostrils, 
on its way down to the lungs. It will also be found full 
of foramen or small holes through which the nerves from 
the brain and various blood vessels pass to the organs 
situated in the head, such as the tongue, lips and the 
various glands in and around the head. 

Then there are the cavities in which the ej^es are sit- 
uated, one on each side of the head, called the orbital 
fossa. In examining this fossa you will find a small 



OSTEOLOGY 11 

opening or foramen, through which the optic nerve 
passes in coming from the brain to the eye. This is the 
nerve of sight. Then the most important part of all to 
consider is the cranial cavity in which that very import- 
ant organ is situated called the brain, which controls all 
the various functions and movements of the body. 

Another important point is the situation of the ear 
drum. It is situated in the hardest bone found in the 
whole skeleton, called the petrosal. The nerve that gives 
the function called hearing comes from the brain down to 
the petrosal bone and enters by a small foramen or hole 
into the drum of the ear to give hearing. This nerve is 
called the auditory nerve. 

2. Cervical Vertebrae or Neck Bones. — These 
bones are seven in number. The first and second bones 
proceeding from the head receive special names. The 
first one is called the atlas, from which the head is sus- 
pended and to which it is attached; it somewhat resem- 
bles the body of a bird with wings extended. The second 
bone receives the name of dentata. This is the bone 
which allows the head to turn in any direction, hence it 
is sometimes called the axis or pivot of the neck. Be- 
tween these two bones, on the upper surface, is the only 
place where the spinal cord is not covered with bone, a 
spot about three-fourths of an inch in diameter. The 
next four bones receive no name, and are about the same 
in size and length. The last, or the seventh bone, is 
only about one half the length of the preceding ones and 
receives no special name. 

3. Dorsal Vertebrae or Back-Bone. — Dorsal 
bones are eighteen in number. The chief point of in- 
terest about them are the height of the spines on the 
upper surface of the bones. These large spines form the 
withers of the horse, as will be noticed in the skeleton. 
On either side of these bones the ribs are attached, 18 
pairs corresponding with the number of bones in this 
region. 

4. Lumbar Vertebrae (or the bones which form 



12 VETERINAHY ANATOMY 

the skeleton of the loins) . These bones are six in num- 
ber, and they are situated immediately above the kidneys. 

5. Sacral Vertebrai: or Rump Bones. — There 
are five of these bones in the young horse, but in the 
adult they unite as a single bone, somewhat triangular- 
shape. These are situated between the upper hip bones 
and help to form the rump. Beneath these bones the 
bladder is situated. 

6. Coccygeal Vertebrae or Tail Bones. — These 
are 18 to 20 in number. There is no complete canal, like 
in the previous vertebraes, for enclosure of the spinal 
cord. 

7. Pelvic or Hip Bones. — The pelvic bones are 
flat, but somewhat irregularly-shaped, and they form 
the sides, floor, and part of the roof of the pelvic cavity. 
Above they are connected with the sacrum, and below 
united to each other, in the adult, by ossification (union 
of bone). In the young animal, as above stated, and 
especially in the foetus, each side consists of three parts, 
which retain their names of ilium, ischium, and pubis, 
even after union by ossification. They all three meet 
in the acetabulum, or articular cavity for the femur or 
hip bone. 

8. Sternum or Breast Bone. — This bone is small 
and short in the horse and is situated on the lower surface 
of the chest cavity. The principle points to be noted in 
this bone are that of its softness, and that the first eight 
pairs of ribs are attached to it on either side. This bone, 
in the horse resembles the keel and cut-water of a boat. 

9. Ribs. — In the horse the ribs usually number 
eighteen on each side. They extend in a series of arches 
of varying curvature from the dorsal vertebrae above, 
towards the sternum and sides of the abdomen below. 
Their shape, in a great measure, determines the con- 
formation or shape of the thorax or chest cavity; they 
protect its contents, and materially aid in its contraction 
and expansion. They are continued downward and for- 



OSTEOLOGY 13 

ward by a small piece of cartilage or gristle, and are 
just slightly attached to the breast bone or sternum ; these 
are called the false ribs. Note that, starting with the 
first rib, they get longer until the ninth rib is reached; 
they then get shorter, the last rib being only a few 
inches long. 

10. Scapula or Shoulder Blade. — The scapula 
is a flat bone situated on the antero-lateral (front side) 
surface of the thorax or chest cavity, it is triangular in 
shape, the base being turned upwards. The inferior or 
lower extremity articulates with the humerus or shoulder 
bone. 

11. Humerus or Shoulder Bone. — The humerus 
is a long bone extending from the scapula to the radius 
and ulna in an oblique direction downwards and back- 
wards. Like all long bones it possesses a shaft and two 
extremities and two articular surfaces. 

12. Radius, or Bone or the Fore-arm. — The rad- 
ius is a long bone, and occupies a vertical position be- 
tween the humerus and the carpus. 

13. Ulna, or Bone of the Fore-arm. — The ulna 
is an irregular bone, in form triangular, with the base 
uppermost, and is placed on the supero-posterior or 
(upper and back) part of the radius. 

14. Carpus, or Knee. — The carpus, knee or wrist, 
as it is incorrectly termed in quadrupeds, is composed of 
seven and often of eight small, irregular bones arranged 
in two rows of three each, one above the other, the seventh 
being at the back of the three in the upper row, and the 
eight, when present, in a similar position with respect 
to the lower row. Their names are as follows : scaphoid, 
lunar bone, cuneiform bone, trapezium, trapezoid, os 
magnus, unciform, pisiform, which is not alwaj^s present. 

15. Os Metacarpi Magnus, JMetacarpal or Can- 
non Bone. — The large metacarpal, or cannon bone, is a 
long, straight bone, placed in a vertical direction. Its 



14 A^TERINARY ANATOMY 

superior or upper extremity articulates with the carpus 
and its inferior or lower extremity articulates with the 
OS suffraginis and the two sesamoids. 

16. OssA Metacarpi Parva^ or Splint Bones. — 
The two small metacarpal, or splint bones, tuberous in 
form (marked or covered with projections) at the carpus 
and tapering distally '(lower portion), are attached to 
the large bone, one on each side of its posterior (back) 
surface, by ligaments in the young animal, and by ossifi- 
cation (union of bone) in most grown up, and in all old 
animals. 

17. Proximal Phalanx^ Os Suffraginis, or 
Large Pastern Bone. — The os suffraginis, or large 
pastern bone, passes obliquely downwards and forwards, 
and articulates with the cannon bone above, and the 
median phalanx or os coronae below. It belongs to the 
class of long bones. 

18. Great Sesamoid Bones. — These bones, two in 
number, are placed side by side at the postero-inferior 
(back and lower) part of the metacarpus and postero- 
superior (back and upper) part of the os suffraginis; 
they are irregular in shape, their back parts are covered 
with cartilage, for the passage of the flexor tendons of 
the digit or the last four bones of the limb. Their su- 
perior or upper surface is roughened, and their sides, 
which are grooved for the reception of the suspensory 
ligament. (This is called the fetlock joint.) 

19. Median Phalanx, Os Coronae, or Small 
Pastern Bone. — The second phalanx, os coronae, or 
small pastern bone, has no marrow canal, and belongs to 
the class of irregular bones. It is inchned, like the os 
suffraginis, obliquely downwards and forwards, and is 
partly covered by the hoof. The upper portion of this 
bone articulates with the os suffraginis and the two sesa- 
moids, the lower part articulates with the os pedis. 

20. Distal Phalanx, Os Pedis, or Coffin Bone. 



OSTEOLOGY 15 

— The third, or ungual phalanx, os pedis, or coffin bone, 
is an irregular bone situated within the hoof, and, when 
in a health}^ state, corresponding somewhat to it in shape, 
being semilunar in form, with the convexity to the front, 
This bone is verj^ hard and porous, having many open- 
ings for the transmission of arteries and veins. In this 
bone we notice the wall, the sole, the tendonous surface, 
the articular surface, and the alae or wings. This bone 
articulates with os coronae superiorly (upper) and pos- 
teriorly it articulates with the os navicular bone. 

21. Os Naviculare. — The naviculare, third or 
small sesamoid, or shuttle bone, is an irregular bone, sit- 
uated with its long axis transversely, behind and below 
the OS coronae, and behind the os pedis, with both of 
which it articulates, the articulation of the three form- 
ing the so-called coffin joint. The lower surface of this 
bone is important as it is covered with cartilage, and 
together form a kind of a pully over which plays the 
great flexor perforans muscle. The remaining portion 
of the anterior limb or front leg, will be considered under 
anatomy of the foot. The navicular bone can be plainly 
seen on Plate VII, anatomy of the foot. 

22. Femur or Thigh Bone. — The os f emoris, femur 
or thigh bone, the largest, thickest, and strongest bone in 
the body, belongs to the class of long bones, and is placed 
in a direction obliquely downwards and forwards, artic- 
ulating with the cup-shaped cavity in the pelvic or hip 
bones superiorly (or upper), and with the tibia and 
patella inferiorly (or below). This bone is roughened 
for the attachment of the powerful muscles of the hip. 

23. Patella, or Stifle Bone. — This, the knee- 
pan or stifle bone, is placed in front of the pully-shaped 
groove of the femur. It is very compact, its front surface 
being irregular, round and very much roughened, for 
ligamentous attachment, and its posterior (or back) sur- 
face very smooth to articulate w^ith the groove in the 
femur, presenting two depressions divided by a ridge, 



16 VETERINAEY ANATOMY 

the inner being the larger, and in the fresh state enlarged 
still more bj^ projecting cartilaginous lip, or elevation. 
The patella increases the power of the hind leg, and it 
is this bone that causes stifle joint lameness when it 
slips out of the groove in which it glides normally. 

24. TiBiA^ OR Legbone. — The tibia or leg bone, is a 
long bone, larger at its upper than its lower end, situated 
between the femer and the astragalus, slanting down- 
wards and backwards. This bone is three-sided, posses- 
sing outer, inner and back surfaces, all of which are wider 
above than below. This bone gives attachment to the 
flexor muscles of the hip. 

25. Fibula. — This is a long slender bone, little de- 
veloped in the horse, and is an appendage to the tibia, 
being attached to the outer side of that bone, and extend- 
ing from its head to its lower third, to which it is affixed 
by a ligament ; the space between the two bones is called 
the tibial arch. The fibula gives attachment to the per- 
oneus muscle, the muscle that is supposed to be severely 
contracted when an animal is affected with string-halt. 

26. Tarsus, or Hock Bones. — The tarsus, or hock, 
corresponding to the ankle-joint of a man, is composed 
of six irregular compact bones, situated between the 
lower end of the tibia and the superior or upper extremity'' 
of the metatarsus; they are arranged in two series; one 
consisting of the cuboid and three cuneiform bones, the 
magnum, medium, and parvum, corresponds to the lower 
row or carpal bones ; the other upper series consists of the 
astragalus and calcaneum; the first, forming with the 
bone above the mobile portion of the joint, may be said 
to correspond to the upper row of carpal bones, while 
the latter, being the lever bone, corresponds to the trapez- 
ium. These bones, like those of the carpus, are thickly 
covered with cartilage on their articular surfaces, which 
acts as a protection against concussion. It is these bones 
that become diseased and united when an animal is af- 
fected with bone spavin. The calcaneum bone which 
forms the prominent part, termed the point of the hock, 



OSTEOLOGY 17 

and corresponds to the heel-bone of man. This bone 
gives attachment to the calcaneo-cuboid hgament, and 
it is this ligament that is sprained or ruptured in curb of 
the hock. 

28. Metatarsus, or Os Metatarsi Magnum. — 
This bone presents the same general appearance as the 
large metacarpal or cannon bone, from which it differs 
principally in being about one-sixth longer and flattened 
from side to side. It is rounded and more prominent in 
front. This bone articulates above with the tarsus bones, 
and its lower portion articulates with the os suffraginis. 

28. OssA Metatarsi Parva, or Splint Bones or 
THE Hind Leg. — These also present the same general 
form as the small metacarpal bones of the front leg ; the 
outer is the longest and largest, and has the largest head, 
with two surfaces which articulates with the cuboid bone ; 
the inner one has also three articular surfaces, two for 
small, and one for the middle cuniform bones. The two 
surfaces on each head articulate with corresponding ones 
on the large metatarsal bone. The remaining bones of 
the hind extremity, viz. : the three phalanges, with their 
three accessory bones, so closely resemble the correspond- 
ing bones of the fore extremity, that it seems at first 
sight difficult to distinguish one from the other; the 
chief differences being, that the first phalanx of the 
hind extremity is longer; its upper end larger, and its 
lower end smaller, than in the fore extremity. 



18 VETERINARY ANATOMY 

COMPARATIVE OSTEOLOGY. 

In this section we shall endeavor to point out where 
the skeleton of the domesticated animals, other than the 
horse, differ from the typical skeleton of the latter in 
any important particular. The following descriptions 
are therefore in all cases comparisons, where comparison 
is possible, between the typical skeleton and the skeleton 
in question. 

RUMINANTIA. 
(Cud Chewing Animal.) 

In this class we take the ox as the animal which 
represents the best for our purpose, the family of rumi- 
nating or cud-chewing animals, as cattle, sheep and 
goats. 

The Skull or Cranium. — 'In the skull of the ox an 
important feature is the development of the frontal or 
forehead bone, which extends from below the eyes to the 
back of the skull, forming the entire forehead and crest 
or top, in the middle of which is the forehead tuberosity 
or knob-like elevation, which is very large in hornless 
animals. Springing from the sides of the top are two 
processes, varying in size and shape, but corresponding 
to the shape of the horns, which they support. 

Vertebrae. — The true vertebral column is made up 
of 26 bones divided into seven cervical or neck-bones, 13 
dorsal or back-bones, and six lumbar or loin bones. 

Cervical or Neck-Bones. — The bodies of these 
bones are shorter than those of the horse, but same in 
number. 

Dorsal or Back-Bones. — These bones are longer 
than in the horse, but have the same general form. It 



OSTEOLOGY 19 

gives attacliment to 13 ribs on each side in the same 
manner as those of the horse. 

Lumbar or Loin Bones. — The hmibar vertebrae 
are longer and thicker than in the horse, their bodies 
being more round on the sides and lower surfaces. 

Sacrum^ or Rump Bones. — The sacrum is larger 
and more arched, and the upper surface more round than 
in the horse. 

Coccygeal or Tail Bones. — The tail bones are from 
15 to 20 in number, are strong and rougher than those 
of the horse. 

Pelvis or Hip Bones. — The pelvis is larger, but 
presents the same general appearance as in the horse. 

In studying the bones of the limbs in ruminants, the 
only point of difference is in bones below the knee. The 
large metacarpal bone presents a vertical groove down 
its front, which marks the original division of the bone 
into two bones. The lower extremity is divided by a 
deep groove into two articulations, each resembling the 
single one of the horse. The outer one being always the 
smaller, a rudimentary metacarpus is placed on the back 
and outer surface. The pasterns and sesamoids in either 
limb are double, one set forming each digit; they are 
small and narrow, the coffin bone resembles half of that 
of the horse, equally divided. 

In the aged ruminant, two bones are commonly 
found in the heart, and may be termed the cardiac bones. 
They are found related with auriculo- ventricular rings. 
In shape they present three angles, three borders, and 
two surfaces. The left bone is somewhat smaller then 
than the right. 

OMNIVORA. 

Animals eating both vegetable and animal food. 
The omnivora are represented in veterinary anatomy 
by the hog. 



20 VETERINAKY ANATOMY 

CARNIVORA. 

An order, suborder, or family of mammals, especially 
wild animals, including the dog and cat, etc. Animals 
that eat flesh. 

In this order our description alludes mostly to the 
dog. 

AVES. 

The scope of the present work will allow only very 
brief treatment of this part of the subject. 

Of or pertaining to Birds, Poultry, Etc. 
The bone tissue or substance of birds are exceedingly 
compact and hard, white in color ; and some of the bones 
are pneumatic, or contain air instead of marrow, notably 
these are bones of the skull, the sternum or breast bone, 
and the upper bones of the limbs. There are a great 
variety in the amount of pneumaticity or air possessed 
by the skeleton of different species, but it is not neces- 
sarily determined by the flying power of the animal. 



CHAPTER II. 
ARTHROLOGY. 

What is known regarding the articulations of bones 
of joints. The several bones which form the skeleton 
are united by means of certain soft structures, forming 
a number of articulations or joints, the study of which is 
termed arthrology. 

Before considering the different forms of joints, it 
will be advisable to describe briefly the various tissue, 
other than bone, which enter into and contributes towards 
their formation. These are chiefly cartilage, connective 
and elastic substance or tissues, and fat. 

Iln health, one bone never comes directly in contact 
with another, cartilage or fibrous tissue being always 
interposed ; an exception to this exists in the adult skull, 
most of the bones of which become firmly united by ossifi- 
cation of the interposed soft material. 

Cartilage. — Cartilage, known also by the familiar 
name of gristle, is a firm, bluish-white elastic animal 
substance, somewhat transparent, resilient, and flexible, 
possessing great cohesive power. That which forms the 
original basis of the bony framework is termed tempor- 
ary, and that which persists in the adult, permanent 
cartilage ; the former disappears as it is replaced by bone, 
but the latter, of which alone we have to treat here, never 
under normal circumstances become ossified. Cartilage 
consists of corpuscles or cells, usually embedded in an 
intercellular substance. 

The articular cartilage is important as it encrusts 
the articular surfaces of bones, helping to form joints by 
supplying smooth, elastic cushions, which diminishes both 
concussion and friction. 

Connective Tissue (White fibrous tissue.) — In one 

21 



22 VETERINARY ANATOMY 

form or another this tissue is found in all parts of the 
body. The chief varieties are the areolar and the fibrous ; 
the former serving as a connecting medium, and support 
to the various organs, and to the structures of which 
they are formed. It appears as a loose, transparent 
mesh, its interwoven bundles forming spaces termed the 
areolar or cells. 

Connective tissue contains nerves and blood-vessels, 
for the supply of neighboring structures as well as for 
its own nourishment. When healthy it is little sensitive 
to pain. 

Yellow Elastic Tissue. — This differs from the 
white or connective tissue in being yellow, elastic, and 
not so tough or strong. Its fibers are usually large but 
when mixed with the white tissue in tendons the size 
diminishes. 

Yellow elastic tissue is found nearly pure in the liga- 
mentum nuchae, and tunica abdominis, the coats of the 
largest arteries and elsewhere. The lungs contain a 
large quantity of this tissue. 

When white fibrous tissue is boiled gelatine is ob- 
tained, which is not the result of boiling the yellow elastic 
tissue. 

Adipose Tissue. — Fat or adipose tissue consists of 
cells containing an oily material, and arranged in isolated 
groups, or slightly separated by meshes of areolar tissue. 
It is found in many parts of the body, and varies greatly 
in quantity; in joints it occurs between the ligaments, 
and serves the purpose of a packing material, while in 
the form of medulla or marrow it occupies the cavities 
of bones. In fat cell a nucleus is very rarely visible. 

Ligaments. — Ligaments are dense, fibrous, con- 
necting structures. They exist in most articulations, and 
are made up principally of white fibrous tissue. There 
are two kinds — capsular or bursal, and funicular or bind- 
ing ligaments. 

Capsular ligaments are membranous structures en- 



ARTHROLOGY 23 

closing true joints. They consist of a dense interlace- 
ment of fibers attached to bones, round the edges of the 
articular cartilages ; some regard them as a continuation 
of the periosteum or the covering of bone. They are 
never closely applied, their use being to form cavities 
round the joints, enclosing and protecting the synovial 
or lubricating apparatus inside. 

Funicular or binding ligaments consist of rounded or 
flattened cords, or bands of fibrous tissue, passing from 
one bone to another, firmly attached to roughened por- 
tions of their surfaces. They hold the bones in their 
places, at the same time allowing the requisite amount 
of motion in the joints. Ligaments which are situated 
between bones are often termed interosseous. Annular 
ligaments are those which bind down and protect the 
tendons of muscles in certain joints, converting grooves 
in the bones into channels or tubes which are lined with 
synovial membrane, and through which the tendons play. 

Some ligaments are composed almost entirely of yel- 
low elastic tissue, such as the ligamentum nuchae (the 
elastic ligament of the neck) and the ligaments connect- 
ing the vertebral arches '(arches between the bones of 
the spinal column). 

Synovial Membranes. — These are thin membranes 
lining the capsular ligaments of joints, or they are inter- 
posed elsewhere between structures which move one upon 
another, and which would otherwise be injured by the 
friction. Near the borders of articular cartilages the 
membrane is generally found as a projecting fold, the 
projection being due to a small pad of fat, interposed 
between the membrane and the capsular ligament. These 
projections were once erroneously termed synovial 
glands, but their use is probably to assist in forcing the 
synovia between the opposing surfaces of cartilage. 

Synovia. — Synovia or joint oil, is a viscid, transpar- 
ent fluid, colorless, or pale yellow, physically resembling 
oil, but it contains very little fatty material, consisting 
chiefly of albumen, salts and water ; it is secreted by the 



24 VETERINAHY ANATOMY 

cells of the inner surface of the synovial membrane. 
When an animal is in active exertion, there is a greater 
demand for joint oil than when at rest, consequently 
there is an increased secretion of it. 

Classes of Joints. — Joints may be divided into three 
classes — Immovable, movable and mixed. 

Motion in Joints. — The following terms express 
the various movements allowed by joints — Eoctension 
tends to bring two bones as nearly into a straight line as 
the structure of the joint will permit; f lemon is the re- 
verse of this, and diminishes the angle that extension 
increases; abduction expresses the outward movement 
of a limb or bone from the central line of the body ; ad- 
duction is the reverse action ; rotation signifies the partial 
revolution of a bone or number of bones, as it were, on 
their own axis ; circumduction implies the movement of 
the lower end of a bone or limb, where it describes a 
cui*ve, as the bow of a circle, ellipse, etc. The term glid- 
ing explains itself, and is peculiar to movable and other 
joints having no frictional surfaces. 

(Important points of joints to be considered will be 
described on Plate I by Roman figures to correspond 
with those given below. 

Joints of the Front Leg. 

I. Shoulder Joint. — This joint is formed by the 
lower end of the scapula, or shoulder blade, and the up- 
per end of humerus or shoulder bone. This is a ball-and- 
socket joint, and is held in its place by ligaments and 
muscles. This belongs to the class of rotation joints, 
its action is outward, inward, backward and forward. 

II. Elbow Joint. — This joint is formed by the 
lower part of the humerus and the upper portion of the 
radius and ulna. It is covered with ligaments and mus- 
cles similar to the above mentioned joint. This is a 
hinge joint the action of which is only forward and 



ARTHROLOGY 25 

backward, or flexion and extension. It has no lateral 
movement. 

III. Carpus or Knee Joint. — This joint has been 
explained very thoroughly in the previous chapter. There 
are three separate articular surfaces in this joint. This 
joint has a large capsular hgament, and has binding liga- 
ments one above the other, the seventh being at the back 
of the three in the upper row, and the eight, when pres- 
ent, in a similar position with respect to the lower row. 
Thus there are three separate articular surfaces in this 
joint. The upper surface of the carpus articulates with 
the radius; this forms the hinge joint of the knee and is 
where flexion and extension takes place. Another artic- 
ulation between the upper and lower carpus bones give 
slight motion to the knee, but not so much as the upper 
articular surface. Between the lower surface of the 
lower row of carpus bones and the upper extremity of 
the metacarpal, or cannon bones, is another articular 
surface which gives motion to the knee. This joint has 
a large capsular ligament, and has binding ligaments 
inside and outside. In addition to the flexion and exten- 
sion movement the knee joint possesses, it also serves as a 
cushion and relieves concussion of the fore limb. 

IV. Fetlock Joint. — This joint is formed above 
by the lower portion of the metacarpal, or cannon bone, 
and below by the part of the os suf fraginis or the large 
pastern bone. At the back of this joint there are two 
small bones called the sesamoid bones. This joint has a 
capsular and two lateral binding ligaments. The mo- 
tion of this joint is a backward and forward or flexion 
and extension, same as that of the knee. 

V. Pastern Joint. — This joint is situated just 
above the hoof, and is formed by the lower end of the 
OS suffraginis or large pastern bone and the upper end 
of the OS coronae or small pastern bone. It has a cap- 
sular and lateral binding ligaments, same as the fetlock 
joint. It also has the same motion as the fetlock joint, 
and is often the seat of what is termed a high ringbone. 



26 VETERINARY ANATOMY 

VI. Coffin Joint. — This joint is situated within 
the hoof. It is formed above by the lower end of the os 
coronae or small pastern bone, and below by the upper 
surface of the os pedis or coffin bone. Immediately be- 
hind this joint, and articulating with the two mentioned 
bones, is the navicular, or shuttle bone— it gets its name 
from its likeness to the shuttle of a sewing machine. This 
bone when diseased is the seat of navicular disease, or 
coffin-joint lameness. The action of this joint is very 
slight forward and backward. 

Joints of the Hind Leg. 

VII. Hip Joint. The hip joint is formed by the 
pelvis and femur bone. This is a true ball-and-socket 
joint similar to the shoulder joint. It has a capsular, 
and is called the round ligament, in the joint, holding 
the head or ball on the femur in the socket of the pelvis. 
This can be seen plainly by examining the joint. This 
round ligament is important, as it often becomes strained, 
being the seat of hip joint lameness. It is also held 
together by the strong muscles of the hip. Its motion is 
rotation similar to that of the shoulder joint. 

VIII. Stifle Joint. — This joint is formed above 
by the lower end of the f emer, or hip bone, and the upper 
end of the tibia or thigh bone. These two bones in front 
form a pulley-like surface on which the patella, or stifle 
bone, is situated. This bone, when the joint is in motion, 
glides up and down over the pulley-like surface. It some- 
times becomes displaced, and this is termed dislocation of 
the patella or stifle bone. This is an important point to 
notice about this joint. It has a capsular and lateral, or 
binding ligament, which hold the stifle bone to its place 
as it plays upon the pulley-like pixjcess of this joint. The 
action of this joint is only forward and backward or 
flexion and extension. It has no lateral or side motion. 

IX. Tarsus or Hock Joint. — This joint contains 
six bones. The two upper bones, one of which is a pulley- 



ARTHROLOGY 27 

like bone placed in front, and the other placed behind, 
forms that portion of the hock which is called the point 
of the hock to which the muscles of the gambe are at- 
tached. It can be easily seen or felt. The upper surface 
of these two bones articulate with the lower portion of 
the tibia or thigh bone, and forms a true articulation of 
the hock joint. This part is what gives most of the mo- 
tion to the joint. Below these are three other small, ir- 
regular bones, placed one upon the other, having an 
articular surface between them. Immediately behind 
these three small bones is what is called the cuboid bone. 
This bone also articulates with the three small irregular 
bones, helping to form the articular surface of the hock. 
The lower articular surface helps to give a small amount 
of motion to the joint. This joint is the seat of bone or 
bog spavin due to severe sprains, or poorly conformed 
joints. 

Fetlock, pastern and coffin joints of the hind leg are 
so closely allied to those of the fore leg that it is not 
worth while discriminating between them. 



CHAPTER III. 

MYOLOGY. 

The branch of anatomy which treats of the muscular 
system is called Myology. 

Muscles are the active organs of motion, or locomo- 
tion, each being separated from the other by a thin deli- 
cate membrane made up of connective tissue, which 
forms a sheath for the muscle. A muscle is divided into 
two parts, viz. : muscular and tendinous. The muscular 
part is the larger of the two. It is sometimes called the 
belly of the muscle or flesh. This part is known as 
muscular tissue, and has a reddish, meaty color. At 
both ends of the muscle there is a tendinous part, or the 
hard, white portion of the muscle which becomes attached 
to the bone. All muscles are attached to two or more 
places of different bones, and when contracted, the joints 
of the body are moved. They are well supplied with 
nerves, which give strength and feeling, and also well 
supplied with small blood vessels, from which the muscle 
is fed. Muscles are found in separate groups, all of 
which have different actions to perform. There are two 
kinds of muscles — voluntary and involuntary. The 
voluntary muscles are under the control of the will of 
the animal; example — the muscles of the head, neck, 
back, hip and legs. The involuntary muscles are beyond 
control of the animal, and will act even though the ani- 
mal were asleep — such as those of the heart, the large 
muscular curtain which separates the chest cavity from 
the abdominal cavity, which is one of the great muscles 
of breathing; also the muscles around the chest which 
assist in breathing. 



28 




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EXPLANATION OF PLATE 11. 

Muscles of the Horse. 

This illustration shows the superficial muscles of the 
body after the skin and pannisulus carnosis muscle has 
been carefully removed. This muscle is spread over the 
greater part of the body, which is related externally with 
the skin; internally with the superficial layer of muscles. 
Its action corrugates the skin, and thus enables the animal 
to expel or shake off insects and irritating bodies, its use 
being thus protective to some extent; it also supports and 
binds down the superficial muscles. 



SUPERFICIAL LAYER. 
The panniculus and tunica abdominalis are removed. 



9. 

9' 
10. 
11. 
12. 
13. 
14. 
15. 
18. 
19. 
20. 
23. 
24. 
25. 
26. 
30. 



Abducens. 

Retrahentes muscles. 
Attollens maximus. 
. Attollens anticus. 
Temporalis. 
Nasalis longus. 
Orbicularis palpebrarum. 
Levator labii superioris alaeque 
nasi. 
Dilatator naris lateralis. 
Orbicularis oris. 
Zygomaticus. 
Buccinator. 

Depressor labii inferioris. 
Masseter. 
Levator humeri. 
Trapezius cervicalis. 
Trapezius dorsalis. 
Latissimus dorsi. 
Pectoralis parvus. 
Pectoralis magnus. 
Stern o-maxillaris. 
Subscapulo-hyoideus. 
Antea-spinatus. 
Teres externus. 
Postea-spinatus. 
Caput medium 
of the triceps. 



31. Caput magnum 
extensor brachii. 

33. Extensor metacarpi magnus. 

34. Humeralis obliquus. 

35. Extensor pedis. 

36. Flexor metacarpi externus and 

medius. 

37. Flexor metacarpi internus. 

46. Cervical 

47. Dorsal 

serratus magnus. 

48. Rhomboideus longus. 

49. Superficialis costarum. 

50. Splenius. 

52. Intercostales. 

54. Tensor fasciae latae. 

55. Triceps abductor femoris. 

56. Gluteus; externus. 

61. Biceps rotator tibialis. 

62. Rectus femoris. 

63. Vastus externus. 

65. Gastrocnemius externus. 

68. Flexor pedis perforans. 

69. Peroneus. 

70. Extensor pedis. 

71. Flexor metatarsi. 

72. Flexor pedis accessorius. 

74. Obliquus abdominis externus. 



29 



30 VETERINARY ANATOMY 

Voluntary Muscles. — The voluntary muscles are 
in groups. The first muscle we will call the student's 
attention to, after removing the skin, is the panniculus 
carnosus (not shown in Plate I) , which is a thin muscle, 
and almost entirely covering the body, which is some- 
times accidentally removed by a careless person in skin- 
ing the animal. The action of this muscle is to shake 
the skin when flies or other objects bother the horse. 
This muscle is not shown in Plate I it having been re- 
moved in order to show the more important ones. 

Head Muscles. — At the head there is a group of 
muscles which assist in chewing, or masticating, the food. 

Gullet or Pharynx Muscles. — Around the throat 
is another set of muscles, sometimes called the muscles 
of the gullet, or phaiynx, which assist in swallowing. 

Neck Muscles. — ^The neck muscles are divided into 
two groups, one on each side. The action of these is 
to raise and lower the head, also to turn the neck and 
head from side to side. 

Muscles or the Back. — The muscles of the back 
are generally divided into two groups, one above the 
spinal column and the other below. The muscles above 
the spine assist the animal in running, jumping and rear- 
ing. The muscles below the spine are sometimes called 
the psoae, or lumbar, muscles, situated below the lum- 
bar bones, or the bones of the small of the back. The 
action of these muscles is to assist the animal in getting 
up. These muscles are important, for when paralyzed 
the horse cannot use his hindquarters. Below these 
muscles are the kidneys. 

Hip or Gluteal Muscles. — The muscles of the 
hip are very large, filling in around the hip bones. The 
action of these is much the same as those of the back, as 
they assist in jumping, running, rearing and in flexing 
and extending the hind leg. 

Tail or Coccygeal Muscles. — Here there are four 




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EXPLANATION OF PLATE III. 

Muscles of the Horse. 



Deep 

1. Temporalis. 

1. Stylo-maxillaris. 

2. Rectus capitis anticus major. 

3. Sterno-thyro-hyoideus. 

4. Sterno-maxillaris. 

5. The Trachea. 

6. Scalenus. 

7. Splenius. 

8. Funicular part of ligamentum 

nuchffi. 

9. Rhomboideus longus. 

10. Cervical 

15. Costal 

serratus magnus 

11. Cartilage of prolongation. 

12. Rhomboideus brevis. 

13. TraaSversalis costarum. 

14. Longissimus dorsi. 

15. Serratus Magnus. 

16. External intercostals. 

17. Internal intercostals. 

18. Rectus abdominis. 

19 19. Pectoralis magnus. 

20. Postea-spinatus minor. 

21. Flexor brachii. 



23. 

24. 

25. 



Layer. 

22. Humeralis obliquus. 
22'. Caput parvum (of triceps ex- 
tensor brachii). 
Extensor suffraginis. 
Extensor metacarpi magnus 

divided. 
Extensor metacarpi obliquus. 
25'. Its tendon. 

26, 28. Flexor pedis perforans and 
perforatus. 

29. Obliquus abdominis internus. 

30. Gluteus maximus. 

31. Erector coccygis. 

32. Curvator coccygis. 

33. Depressor coccygis. 

34. Rectus femoris. 

35. Vastus, externus. 

Part covered by triceps ab- 
ductor. 

Biceps rotator tibialis. 

Gastrocnemius externus. 

Plantaris. 

Flexor pedis perforans. 

41. Peroneus. 

42. Flexor metatarsi. 
Extensor pedis (cut across). 



36. 

37. 
38. 
39. 
40. 



43. 



31 



32 VETERINARY ANATOMY 

that are important, one situated on the upper side of the 
tail when straight out, the action of which is to raise 
the tail; two, one on each side of the tail, have the 
power of drawing the tail to either side; the fourth is 
situated under the tail and is the smallest one of the four. 
Its action is to draw the tail down. 

Abdominal Muscles. — The abdominal or belly 
muscles, are four large, flat muscles on each side of 
the abdomen. The outer edge of these muscles is at- 
tached to the outer ends of the false ribs, also to the 
processes of the lumbar bones and the outer angles of 
the pelvic or hip bones. They unite below to what is 
called the linea alba, a hard, white fibrous cord. They 
pass back in the center of the belly and are attached 
to the front of the pelvic bones, called the lower bones of 
the pelvic cavity. About ten inches from where it is 
attached here, passing forward, is a small slit or hole, 
which is called the navel, or umbilical opening. Here 
the navel vessels pass in and out during the foetus life, 
or before the colt is foaled. This is a point of import- 
ance to note, for sometimes at the time of birth this 
opening does not close and allows the bowels to come 
down and form what is known as umbilical or navel 
rupture. 

Before finishing the description of this group of 
muscles a very large, important ligament should be 
noted, which is found spread all over the abdomen of 
the horse. It is of a yellowish color and about one- 
eighth of an inch thick, attached in front to the back 
of the breast bone and to the pelvic bones behind. This 
is the first structure seen after removing the skin from 
the abdomen. This ligament gives great support to the 
organs contained in the abdominal cavity. The action, 
or uses, of the abdominal muscles are to support the or- 
gans contained in the abdominal cavity, to flex the back- 
bone and assist in passing of the feces. In the mare these 
muscles assist in parturition, or foaling. 

Shoulder Muscles.— The shoulder muscles are 



MYOLOGY 33 

veiy large and powerful. There are only three of great 
importance. Two situated on the outside of the scapula 
or shoulder blade are important, as they are muscles 
affected in the disease called shoulder sweeny. The 
other important one is that which passes down over the 
shoulder joint through the groove or pulley-like surface 
on the humerus, or shoulder bone. This is a long, power- 
ful muscle, attached above to the lower end of the scapula, 
or shoulder blade, passing down through the groove men- 
tioned, and is attached to the upper and front part of the 
radius or fore arm bone. Its chief point of importance 
rests in its action in raising the front leg, where it passes 
over the pulley-like surface mentioned, when it becomes 
injured or diseased; it is the seat of shoulder joint lame- 
ness. 

Muscles of the Front Leg. — Muscles of the front 
leg, from the shoulder down, are divided into two separ- 
ate kinds, the extensor and flexor muscles. The exten- 
sor muscles are those which bring the leg forward. These 
muscles above are attached to the bones around the el- 
bow joint, passing down in front of the arm bones. 
About three inches above the knee they become changed 
into the tendinous part of the muscles, or what is called 
the cords of the leg. Some of them are attached to the 
bones about the knee joint, while others pass over the 
front of the joint and are held down to their place by a 
band or ligament, forming a looj), as it were, for the 
tendinous portion of the muscle to glide into when the 
leg is in action. Each one of these loops through which 
the muscles pass are supplied with a synovial membrane 
to secrete the synovia, or oil, which lubricate it during 
action, the same as in the joint. This is a point of im- 
portance, as sometimes, on account of injury or strain 
of this part of the joint through which the muscles plays 
there may be found a small, puffy enlargement contain- 
ing oil secreted by the synovial membrane. This disease 
is called bursal enlargement. 

The flexor muscles are situated at the back part of 



34 VETERINARY ANATOMY 

the leg, attached above to the back part of the elbow 
joint, passing downwards at the back part of the leg. 
About two or three inches above the back part of the 
laiee joint they become tendinous, and from there down 
to the back part of the coffin bone, where two of the prin- 
ciple muscles are attached; these form what is known as 
the back tendons, or cords, of the leg. Some of them 
become attached to the back part of the knee, same as 
the muscles on the front part of the leg, while the other 
two principal tendons pass through a loop formed by lig- 
aments, the same as those mentioned in the front part of 
the knee. In tracing these tendons down from the knee 
to the fetlock, notice that they pass through another 
larger loop or sheath formed at the back of the f etloclc, 
where some of the fibers are attached, while others con- 
tinue down at the back part of the pastern bones, and 
are attached to the os pedis or cofRn bone. These ten- 
dons are important, because when they are strained the 
fact is spoken of as the strain of the back tendons. The 
action of these muscles is to flex the leg, bend the knee, 
pastern joints and fetlock. 

Muscles of the Hind Leg. — These are also divided 
into two groups, extensor and flexor. The extensor mus- 
cles are situated in front of the hind leg. They are at- 
tached above, around the stifle joint, and pass down- 
ward in front of the tibia, or thigh bone, one being at- 
tached to the front part of the hock. The other passes 
through sheaths, or loops, supplied by a synovial mem- 
brane, formed by ligaments, to hold the muscles firm in 
front while the leg is in action. In tracing them down, 
in front of the shin bone to the fetlock, note that they 
pass through loops, or sheaths, and continue down in 
front of the pastern bones to where they are attached. 
The action of these is to bring the leg forward. 

The flexor muscles of the hind legs are attached, 
above, around the back part of the stifle joint. In trac- 
ing them down it will be found that they become tendon- 
ous. Two of the principal ones pass down to that part 
of the hock joint, which forms the point known as the 



MYOLOGY 35 

cap. These form what is called the gambe of the leg, and 
are partly attached at the point of the hock, and other 
part passing down to the fetlock joint through a loop, 
or sheath, along the back part of the pastern bones, and 
are attached to the os pedis or coffin bone of the foot. 
This muscle, from the hock down, forms one of the back 
tendons of the hind leg. Another important muscle is 
found passing down underneath those already men- 
tioned, through a loop, or sheath, at the back part of the 
hock, where it is supplied with a synovia sac. This is a 
point of importance, because when it becomes sprained it 
is the seat of what is called thoroughpin. It then passes 
down the back part of the shin bone beneath the other 
tendons already mentioned, through the loop at the fet- 
lock to the back part of the os pedis or coffin bone, where 
it is attached. The action of these muscles are to flex or 
bend the fetlock and raise the hock joint in traveling. 

Involuntary Muscles. — ^Involuntary muscles, or 
muscles not under the control of the will. The first to 
notice are those of breathing or respiration. They form 
a group situated about the chest in such a way as to be 
the means of increasing or decreasing the size of the chest 
cavity. When these muscles expand the chest cavity is 
enlarged, causing the air to rush into the lungs, known 
an inspiration. On the other hand, when these muscles 
contract the air is expelled from the lungs, known as 
expiration. 

The diaphragm is a muscular curtain which separates 
the chest from the abdominal cavity. It also assists 
greatly in drawing the air in, when it contracts. This 
muscle also assists in passing faeces, and in the mare 
foaling. It separates the heart and lungs from the bow- 
els, liver and stomach. This muscle should be carefully 
examined by the students. It can be seen by opening 
any dead animal. 

There is one muscle which is both voluntary and in- 
voluntary. It is situated in the penis, surrounding the 
urethra, or the tube, which carries the urine from the 



36 VETERINARY ANATOMY 

bladder to the penis in the male animal. Its action is 
voluntary while the animal is passing urine. It is invol- 
untary during sexual intercourse, forcing the semen 
down through the penis. 



H 
< 




2 
o 

< 
I 

w 

1/3 

o 



o 

& 

< 
Pi 
< 

Oh 
< 

< 

iz: 
I— I 

K 
^ 

Ed 
< 

Q 
< 

> 
H 

CO 

Ed 
O 



EXPLANATION OF PLATE IV 

Digestive Apparatus of the Horse 



1. Mouth. 




11. Small intestine. 


2. Pharynx. 




12. Floating colon. 


3. CEsophagus. 




13. Rectum. 


4. Diaphragm. 




14. Anus. 


5. Spleen. 




15. Left kidney and ureter. 


6. Stomach (left 


sac). 


16. Bladder. 


7. Duodenum. 




17. Urethra. 


8. Liver (upper 


extremity). 


a. Hard palate. 


9. Great colon. 




b. Tongue. 


10. Caecum. 




c. Soft palate. 



d. Trachea. 

e. Pulmonary artery (divided). 

f. Heart. 

g. Posterior aorta. 



37 



CHAPTER IV. 

SPLANCHNOLOGY. 

Study of large interior organs in any of the four 
great bodily cavities especially those in the abdomen. 

Digestive Organs of the Horse. — The digestive 
organs comprise the alimentary canal and the accessories 
by which the alimentary matter is received and subjected 
to specific actions, which adapt it for purposes of nutri- 
tion. Digestion, therefore, embraces the collective oper- 
ations and changes which the food undergoes in the ali- 
mentary canal. 

The whole digestive track from the mouth to the anus 
which is situated just below the tail, is sometimes called 
the alimentary canal. 

The mouth is an oval cavity at the commencement of 
the alimentary or digestive canal. 'In front of the mouth 
are the lips, one above and one below ; at the sides are the 
cheeks. The mouth is lined with what is known as the 
mucous membrane, in which are several small openings, 
from the glands, which are situated about the mouth. 
Through these the saliva is poured. On the upper part 
of the mouth the mucous membrane is thrown into ridges, 
or folds, from 18 to 20 in number. This is a point of 
importance in connection with bleeding a horse with 
lampas. It is never safe to bleed back of the third bar 
because there is a large artery which runs down through 
the roof of the mouth and enters the hole in the bone 
just before it reaches this bar. The tongue, which has 
the chief nerves of the sense of taste, is situated in the 
mouth; this organ also has a very important part to 
perform in masticating the food and mixing it with 
saliva. The teeth, which also take a very active part in 

38 



SPLANCHNOLOGY 39 

the masticating of food, are dealt with under the head- 
ing of "Teeth." 

Salivary Glands. — These glands secrete the saliva 
that is poured into the mouth while the animal is eating. 
There are only three pairs of much importance. One 
large pair, one on each side of the throat below the ears, 
known as the parotid glands, fill up the space between 
the jaw bone and the neck. This pair has tubes passing 
around and under the lower jaw and up into the cheek 
muscles entering the mouth opposite the fourth molar 
tooth. These tubes, known as steno's ducts are about 
an eighth of an inch in diameter and convey the saliva 
from the glands into the mouth. The next pair are sit- 
uated under the pair just mentioned. Their tubes enter 
into the bottom part of the mouth. The third pair are 
situated under the tongue, one on each side. They pour 
their secretion into the mouth by several small openings 
near the front under the tongue. This can be seen by 
examining the under surface of the tongue closely. This 
is very important fluid in connection with the digesting 
of the food. 

The gullet is a cavity situated just back of the mouth. 
It is chiefly made up of muscles which perform the act of 
swallowing the food. It is lined with the continuation 
of the mucous membrane of the mouth. 

The oesophagus, or the continuation of the gullet, is 
a tube extending from the gullet to the stomach, and is 
used to convey the food to that organ. It is made up of 
two coats, the muscular and the mucous. The former 
contains fibers which, when once the food enters the tube, 
contract behind it, forcing it down to the stomach. Its 
lining is a continuation of the mucous membrane of the 
mouth and the gullet. In tracing the oesophagus or tube 
down the neck from the gullet, note that it passes down 
the left side of the neck, entering the thoracic, or chest 
cavity, between the lungs over the heart through the 
large muscular curtain known as the diaphragm, then 



40 VETERINARY ANATOMY 

enters the stomach an inch or two after passing the 
diaphragm. 

The Stomach. — This organ is very small in the 
horse in comparison with that of the ox. It holds only 
about four gallons, and is situated just back of the cur- 
tain which separates it from the lungs. It lies mostly to 
the left side. The walls of the stomach being composed 
of three coats. That on the outside is called the serous 
membrane, a name ap])lied to membranes which line 
closed cavities, such as the abdominal cavity. The inside 
lining is a continuation of the mucous membrane lining 
the organs before mentioned. The lining in the left part 
of the stomach or the part where the food is prepared 
for digestion is the same color as that of the mouth. The 
lining of the right part of the stomach, which is the true 
digestive part, is of a deep red color resembling velvet, 
and when placed under a microscope has the appearance 
of a honey-comb. When the stomach is empty this mem- 
brane is thrown into loose folds. Several small openings 
may be noticed through which the gastric juice and pep- 
sin from the glands, situated in the walls of the stomach, 
enters. These are very important fluids as they assist 
greatly in digesting the food. The third coat is known as 
the muscular coat already mentioned. Its action is to 
give the stomach a churning motion, rolling the food 
around and mixing it with the juices. The opening to 
the stomach is guarded by a valve which prevents the 
food from passing back through the gullet. There is 
also a valve at the opening of the bowels, preventing any 
coarse, undigested food from entering them. The stom- 
ach is held in its place by five large ligaments, and is 
well supplied by blood-vessels and nerves. Digestion of 
the food takes place very quickly in the horse in com- 
parison to other animals. Frequently a change of food 
or working too soon after eating will interfere with the 
digestion, thus setting up what is known as indigestion. 
This is a very painful disease in the horse. After the 
food is acted upon by the juices in the stomach it changes 



SPLANCHNOLOGY 41 

into what is known as chyme, which passes into the 
bowels. 

The Bow^els. — They are divided into two parts — the 
large and small. 

The small bowels are 72 feet in length, about one 
inch in diameter, and are made up of three coats, same 
as the stomach. The serous coat on the outside contains 
small glands which secrete an oily material to lubricate 
the outside of the bowels, which comes in contact with 
the inner wall of the abdominal cavity. The muscular 
coat, made up of muscular fibers, is situated between the 
other two coats, the same as in the stomach; its action 
is to contract the bowels, giving them motion to convey 
the food along through them. The mucous coat is a 
continuation of the mucous coat of the stomach. Along 
this coat are found small glands known as villi lacteal; 
these absorb the nourishment from the food as it passes 
along through the bowels and pours it into the blood. 
The small intestines or bowels are attached on the upper 
side to what is known as the mesentery, which is attached 
above to the roof of the abdominal cavity. It can be seen 
in any of the smaller animals upon examination. About 
six inches from the stomach, in the bowels, are found 
two' openings. One of these receive the heapitic duct, 
a tube for the purpose of carrying the bile from the liver 
to be poured in on the food as it passes through the 
bowels. The other opening is for the duct of the gland 
known as the pancreas. It secretes a clear fluid known 
as the pancreatic juice. These juices act on the food in 
the first part of the small intestines, changing it into 
chyle. After this, the action of the rest of the intestines 
is to absorb the nourishment out of the food as it is 
passing back. The small intestines and stomach, when in 
a healthy condition, should be found empty one hour after 
food has been eaten. The small bowels or intestines are 
situated mostly on the left side just behind the stomach. 

The large bowels have three coats, the same as the 
small ones. The first part of the large bowels is known 



42 VETERINARY ANATOMY 

as the blind bowel or caecum, and is about three feet in 
length ; this is generally the first thing to protrude when 
opening a horse's abdominal cavity. Its use is to act as a 
reservoir to hold the water and fluid of the food; from 
this organ the water and fluid parts are mostly taken up 
into the system. The next part of the large bowels is 
known as the large colon; it lays along the floor of the 
abdominal cavity, is about nine feet in length and is 
doubled on itself three times. In this bowel the solid 
part of the food is found. Here digestion is brought 
about by the contraction and expansion of the muscles 
of the bowel and the nourishment taken from it, after 
which it is worked back out of this bowel and enters 
what is known as the floating colon. This is about ten 
feet in length and about two inches in diameter, or double 
the size of the small bowel. It is thrown into folds or 
pleats, and as that portion of the food containing no 
nourishment passes through it is worked into balls which 
pass back and are emptied into the rectum or back bowel. 
This is situated at the back part of the abdominal and 
pelvic cavity back of the small bowels or intestines and 
like them, is suspended by a fold paritoneum. 

The rectum or back bowel is sometimes known as 
the straight bowel. 'It is about 18 inches long and forms 
the last part of the bowels or intestines. Its coats are 
a continuation of those of the large bowel, but each is 
thicker and heavier. Above this bowel are the bones 
of the sacrum, below it, in the horse the bladder and 
other small glands. Below the rectum of the mare are 
situated the womb and the vagina, the latter being the 
passage into the womb from the outside. The bones 
which help to form the pelvic cavity are situated at the 
sides, and at the back immediately under the tail is what 
is known as the annus-. The use of the rectum is to hold 
the balls as they pass back from the floating colon. When 
the rectum becomes so full that there is pressure on the 
sides of the wall thus stimulating the nerves the muscular 
coat contracts and forces the contents back towards the 



SPLANCHNOLOGY 43 

annus. At the same time the muscles of the annus di- 
late, causing the faeces to pass out. 

Accessory Organs of Digestion. — In the abdom- 
inal region these organs are the Liver, the Pancreas, and 
the Spleen. 

The Liver is the largest gland in the body and is sit- 
uated between the stomach and the diaphragm. The liver 
of the horse weighs from ten to twelve pounds. It is of a 
dark brown color, well supplied with blood and nerves, 
and is held in place by several strong ligaments. A bit- 
ter, greenish colored fluid called the bile is secreted from 
the liver and emptied into the digestive system, where it 
plays an important part in its action on the food. There 
is no gall bladder in the horse, but simply a tube passing 
from the liver to the small bowel into which it empties the 
bile about six inches back of the stomach. It is impor- 
tant to note that it is in this tube that gall stones some- 
times collect. 

The Pancreas is another very important gland. It is 
of a grayish, fatty color, and may be found near the roof 
of the abdominal cavity in front of the kidneys. The 
Pancreas secretes a clear, colorless fluid called the pan- 
creatic juice. This fluid, like the bile from the liver, also 
plays an important part in the digestion of food. It is 
carried down from the Pancreas by a duct or tube empty- 
ing into the small bowel just back of that of the liver. 

The Spleen is a long, flat gland about fifteen inches 
in length, situated along the left side of the stomach and 
to which it is closely attached. It is of a grayish red color 
and feels quite soft. It is ductless, there being no secre- 
tion passing from it. The function of this gland is not 
clearly understood, but by many it is supposed to regu- 
late the temperature of the stomach during the process 
of digestion and to act as a reservoir for the blood. Some 
speak of it as the burying ground of the red corpuscles. 
It is well supplied with blood vessels and nerves and 
weighs about two pounds in an average sized horse. 



44 VETERINARY ANATOMY 



RUMINANTIA. 



DiGESTmE System. — The lips of an ox are thick and 
hard. The upper has no hair on it and varies in color 
with the color of the animal. When cattle are in good 
health this space is always moist. 

The cheeks on the inside are covered by many small 
rough processes, which give them a very rough appear- 
ance. 

The Tongue of the ox is stronger than that of the 
horse and is more movable. It is very thick and heavy 
at the back, pointed at the front end and the upper part 
of it is very rough. It is by means of the tongue that the 
ox takes most of the food into the mouth. 

The Salivary glands are similar to those of the horse. 

The Teeth differ very much from those of the horse. 

The ox has no front teeth in the upper part of his 
mouth, their place being taken by a pad of cartilage or 
gristle. This pad takes the place of the upper row of 
front teeth. The lower row of teeth press against it when 
the animal is cropping grass. This accounts for the fact 
that cattle do not do as well on short grass as horses. 

The front teeth in the lower jaw also differ from 
those of the horse. They are eight in number, chisel- 
shaped, and are loosely set in the gum. 

The molars, or back teeth, are similar to those of the 
horse, only they are smaller and not so smooth on their 
upper surface. The ox has twenty-four molars or back 
teeth, and eight incisors or front teeth, making thirty- 
two in all. 

The Gullet of the ox is much larger than that of the 
horse. 

The Oesophagus or tube, which carries the food down 
from the mouth to the stomach is well developed, the 
fibers in it being very strong and possessing a double 
action. When the animal is eating they carry the food 
from the mouth to the stomach, and when chewing the 



SPLANCHNOLOGY 45 

cud they act the very opposite, carrying the food from 
the stomach back into the mouth. 

The Stomach. — The student will do well to give 
some time to the study of this important organ of the 
ox, as it is very frequently the seat of disease. 

The stomach has a capacity of fifty-two gallons and 
is divided into four separate and distinct compartments : 
the Rumen or Paunch, the Reticulum or Honey Comb, 
the Omasum or Many-plies, and the Abomasum or the 
true Stomach. In the first three of these the food under- 
goes a sort of preparatory process, while in the fourth the 
process of digestion is complete. 

The Rumen or paunch is very large, and in an aged 
animal fills three-quarters of the abdominal cavity. It 
lies up against the left side of the wall of the abdomen, 
where it is attached and held to its place by the liga- 
ments. Its situation being an important matter, as many 
diseases of the rumen, or paunch, are first noticed on the 
left side. Tapping for bloating is always done on the 
left side because of this fact. The walls of the paunch 
of an ox resemble those of the stomach of the horse, but 
are not so sensitive, and stand a great deal of abuse be- 
fore inflammation sets in. The paunch has two openings, 
both of which are at the front; through one the food 
enters, while through the other it passes out into the 
next division. 

The Reticulum, or honey comb, is the smallest divi- 
sion and resembles a honey comb in appearance. This 
part has little to do with preparing the food. It is pro- 
vided with two openings, one in front, where the food 
enters, the other at the back, where it passes through into 
the third division. In the reticulum, or honey comb, 
the food is softened further by the water that the animal 
drinks which passes directly into the second division. 
The food is here pressed into balls and prepared to be 
forced back into the mouth to be further masticated. 

The Omasum, or many-plies, is the second largest 
division of the stomach. When full it is ovoid in shape. 



46 VETERINARY ANATOMY 

It is placed just behind the second division and at the 
right side of the paunch. The inside is full of folds, or 
layers of membrane, into which all the coarse parts of 
the food pass and roll about until it is fine and well pre- 
pared to pass into the last division. When this part of 
the stomach becomes deranged and the food becomes 
dry and hard between the folds, the disease called im- 
paction of the many-plies, or dry murrain, is the result. 

The Abomasum, or fourth stomach, is the true di- 
gestive part. In it the food is completely digested. The 
walls are redder in color than those of the three first di- 
visions and contain the glands which secrete the acids and 
gastric juices. This stomach has two openings, one 
through which the food enters and the other through 
which it passes into the small bowels. 

The Bowels, or intestines, of the ox are divided into 
large and small bowels. This, together with their struc- 
ture and action resembles that of the horse. The small 
bowels are only half the size of the horse, being about 
one-half inch in diameter, and about one hundred and 
fifty feet in length. The large bowels are not nearly 
so long as those of the horse and are thirty-five feet in 
length. 

The Liver of the ox resembles that of the horse, ex- 
cept that it is provided with a gall bladder which re- 
sembles a pear in shape. This acts as a sac in which to 
store the gall during the time it is not required in diges- 
tion. When digestion is going on the wall of the gall 
sac contracts and forces the gall down to the food. The 
other glands, the pancreas and spleen, resemble those 
of the horse. The juices from these glands have the same 
action in cattle as they have in the horse. 

Rumination, or Chewing the Cud. — Food when 
first taken into the mouth of a ruminant is but lightly 
masticated and mixed with the saliva from the salivary 
glands, after which it is swallowed, passing through the 
oesophagus into the rumen or paunch (first stomach). 
This division acts as a resei*voir or storehouse for food 



SPLANCHNOLOGY 47 

thus eaten quickly. When the animal has time, so to 
speak, he lies down or stands quietly and completes the 
process of mastication of his food by chewing the cud. 
This peculiar act is performed as follows : After being 
softened and mostened by warmth, the food passes from 
the rumen or paunch into the second division — the reti- 
culum, honey comb or second stomach. In this small 
globe-like compartment the food is moistened and com- 
pressed into pellets — the cud. By a peculiar reverse 
action of the oesophagus or gullet these pellets are taken 
back into the mouth for further mastication or chewing. 
When re-mastication is completed it is again swallowed, 
but this time it passes directly into the omasum, many- 
plies or third stomach, and thench to the fourth or true 
stomach. 

Process of Digestion After Rumination. — Fol- 
lowing rumination which, strictly speaking, is the first 
step in the digesting process, the food passes into the 
third stomach. The fine parts pass right along to the 
fourth stomach while the coarser parts are drawn be- 
tween the folds of the membrane in this division and 
worked about until it is fine and ready to pass into the 
fourth stomach, where it becomes fully digested by the 
action of acids and gastric juices which are secreted in 
this part. It then passes into the small bowels, and is 
acted upon by the bile from the liver and the pancreatic 
juice from the pancreas. These juices are emptied into 
the first part of the small bowels through little ducts or 
tubes, which lead from the glands down to the bowels, 
just on the same principle as that of the horse. After 
this, throughout the rest of the bowels, the nourishment 
of the food is taken into the system by means of little 
glands which are situated in the coating of the bowels. 
The nourishment when once in the blood goes to supply 
the different parts of the body, while the part contain- 
ing no nourishment or undigested passes off through the 
back bowels in the form of feces. 



48 VETERINARY ANATOMY 



TEETH. 

Teeth are objects situated in the upper and lower 
jaws. They are made of the same tissues as bone 
but contain 10^/^ per cent, more of earthy salts. This 
fact accounts for their extreme hardness. Unlike bone 
they can stand exposure to air and friction without be- 
coming diseased. Teeth are used to masticate or chew 
the food, and because of the constant change in their for- 
mation and appearance they serve as a guide in telling 
the age of the horse. 

There are three hard structures that enter into the 
formation of the teeth — Dentine or Ivory, Enamel, and 
Cementum, or Crusta Petrosa. 

The Dentine, or ivory, is situated in the upper part 
around the pulp or nerve cavity. It is of yellowish 
color and largely supplied with nerves which pass 
through it from the pulp cavity. 

The Enamel is the hardest substance of the tooth, and 
covers the outside of all the exposed part. This sub- 
stance is characterized by its whiteness and, unlike the 
dentine, contains no blood vessels or nerves. If part of 
the enamel is broken off it is never replaced, and the 
tooth below the broken part generally becomes decayed. 

The Cementum, or crusta petrosa, is found in the 
fang or root and the parts situated below the gum. It 
is the softest part of the tooth. 

Teeth may be simple or compound. Simple as in 
the dog, where the entire exposed surface is covered by 
a solid cap of enamel, which alone is in wear; compound 
or complex, as in the horse, where various tissues are 
in wear. A tooth consists of the following anatomical 
parts: The body, or crown, that part above the gum; 
the table, the part that comes into wear on the top ; the 
neck, the part to which the gums are attached; and the 
fangs or roots, the parts situated down in the bone. 



SPLANCHNOLOGY 49 

There are three kinds of teeth found in the horse, 
the incisors, the canine and the molars. 

The Incisors, or front teeth, situated in the front 
part of the mouth just inside the lips, are twelve in num- 
ber, six above and six below. 

The Canine, or bridle teeth, are often absent in the 
mare. They are four in number, two in the upper and 
two in the lower jaw, one on each side about two inches 
back from the incisor teeth. They are from a quarter to 
three-quarters of an inch above the gum, are round and 
pointed and of no particular use. They resemble the 
eye teeth of other animals. 

The Molars, or back teeth, are twenty-four in num- 
ber, six on each side in the upper and six on each side in 
the lower jaw. With these the food is ground and mas- 
ticated. 

Wolf Teeth are two small, round, pointed tempor- 
ary teeth which vary in size in different animals, situat- 
ed one on each side in front of the molars or back teeth 
in the upper jaw. 

Temporary and Permanent Teeth. — The horse 
has two sets of teeth. The milk are temporary and are 
those that the colt sheds; while those that come in and 
remain without being shed are called the permanent 
teeth. The cutting of the teeth of the foal varies, but 
at or within nine days after birth he has four front teeth, 
two in the center above and two below, and in the back 
part of the mouth twelve molars. At from seven to nine 
weeks four more incisors or front teeth appear, one at 
each side of the two center teeth in each jaw. At nine 
months he gets the last of his milk or temporary teeth, 
these being the corner teeth, two in the upper side and 
two in the lower side of the jaw. At this time he has 
his full set of milk temporaiy teeth, consisting of twelve 
molars or grinders and twelve incisors or front teeth, 
six above and six below, making twenty-four in all. As 
the colt advances in age he sheds all these teeth. He then 



50 VETERINARY ANATOMY 

commences to get permanent teeth. When the age of one 
year is reached, four permanent molars appear, two in 
each jaw, one on each side, behind the three temporary- 
teeth. At two years of age he gets four more back 
molars, one on each side of each jaw. When the age 
of tAvo years and nine months is reached the two middle 
teeth of the temporary incisors, or front teeth of each 
jaw fall out, and are replaced by two permanent incisors 
in each jaw; thus at the age of three years these four 
permanent incisors are up and in wear. At this age, the 
first eight molars, two on each side of each jaw, are shed 
and replaced by eight permanent molars. At four years 
of age he sheds four more front or incisor teeth next to 
those shed at three years, and these are replaced by four 
more permanent incisors or front teeth. At this age, 
too, he sheds the four remaining temporary molars, or 
grinders, which are replaced by four more permanent 
molars. He also gets four more permanent molars at 
the back of the mouth. Thus at the age of four years 
the colt has a full set of permanent molars, consisting of 
six on each side of each jaw, making twenty-four in all. 
At five years of age he sheds the four remaining tem- 
porary incisors or front teeth, which are replaced by four 
permanent incisors, known as the corner teeth. It is 
important to become familiar with the time at which the 
colt sheds his different teeth, for sometimes the caps or 
shells of the teeth do not fall off when they should. These 
should be watched, for they greatly interfere with feed- 
ing and should be removed with forceps. At five years 
of age the canine or bridle teeth make their appearance ; 
thus at the age of five years the colt has all his teeth or 
what is known as a full mouth. 

The following table shows the various changes tak- 



SPLANCHNOLOGY 51 

ing place in the mouth of the horse from the time of 
birth up to the age of five years : 

Hence the horse has — 

— Incisors — Canine — Molars — 

Age Tempo- Perma- Tempo- Perma- 

rary nent rary nent 

At or soon after birth 4 12 

9 weeks 8 12 

1 year 12 12 4 

2 years 12 12 8 

3 years 8 4 4 16 

4 years 4 8 24 

5 years 12 4 24 =40 

The table given below indicates the various changes which occur 
in the mouths of ruminants, and more particularly in the mouth of 
the ox: 

RUMINANTS 

— Incisors — — Molars — 

Age Tempo- Perma- Age Tempo- Perma- 

rary nent rary nent 

At or soon after birth 4 12 

2 weeks 6 1 year 12 4 

3 weeks 8 2 years 8 12 

2 years 6 2 3 years 4 16 

3 years 4 4 

4 years 2 6 4 and 5 years . . 24=32 

5 years 8 

A table giving the number and variety of teeth as they occur in 
the domestic animals and in man may be serviceable as one of handy 
reference, and is herewith appended: 

Incisors Molars Canine Bicuspid Total 

4 6 2 4 

Man — — — 

4 6 2 

6 12 2 

Horse — — — 

6 12 2 

12 

Ox — — — 

8 12 

6 12 2 

Dog — — — 

6 14 2 

6 14 2 

Pig — — — 

6 14 2 

6 8 2 

Cat — — — — = 30 

6 6 2 

The dental formula of the ox is the same as that of all ruminants. 



4 


= 3Z 







— 


= 40 












— 


= 32 












— 


= 42 












— 


= 44 













52 VETERINARY ANATOMY 



RESPIRATORY SYSTEM OF THE HORSE. 

Organs of Respiration. — By the action of these 
organs certain chemical and physical changes take place 
in the blood, the chief of these consisting of absorption 
of oxygen form, and giving off carbonic acid to the at- 
mospheric air, the former change being necessary for 
the elaboration of the fluid, the latter for the elimination 
of a substance which, if retained, would prove injurious. 
The organs of respiration are invariably adapted to the 
wants of the animal and the medium in which it lives. 
Thus insects breathe by air-tubes, opening on the sur- 
face of the body; in the oyster breathing is perfonned 
by fringes ; in fishes by gills ; in the mammelia by means 
of elastic air-receptacles, called lungs, which are en- 
closed in special cavities, and communicate with the at- 
mosphere by means of an air-tube. 

In the horse, who breathes only through his nose, 
the organs of respiration are the nostrils, nasal-cham- 
bers, laiynx, trachea, and in the thoracic cavity, the 
bronchi, bronchial tubes, and the lungs. 

Nostrils. — ^The nostrils are two openings, one on 
each side of the nose. They are held open by the aid of 
cartilage and muscles. About one and one-half inches 
up the nostril on the under side is a small opening about 
the size of a grain of shot. Through this opening the 
duct or tube which carries the tears down from the eyes 
empties into the nose. The nostril is lined* with a thin, 
delicate skin which changes into mucous membrane as 
it passes up into the chambers of the head. 

Nasal Chambers. — These give passage to the air 
from the nostril into the larynx. There are two of these 
chambers, divided in the center by a thin partition or 
cartilage called the septum nasi. These communicate 
with the sinuses of the head. The horse cannot breathe 
through the mouth on account of the formation of the 



SPLANCHNOLOGY 53 

throat, and this compels him to always breathe through 
the nostrils. This is a point which should be remembered. 

Larynx. — This is a cavity made of cartilage. It 
gives passage to the air and also the organ of voice. It 
is situated in the floor of the gullet. This cavity has an 
opening on its upper side, guarded by a valve, which is 
always opened except when the animal is swallowing 
food or water. When the food is being swallowed it 
passes over the valve which closes the opening while the 
food passes over it. This is important, for if the valve 
does not close properly, thus allowing either food or 
water to drop into the windpipe, the animal will have a fit 
of coughing. This is sometimes referred to as "the food 
going down the wrong way." On the outside of this 
cavity of cartilage are found several small muscles which 
help to hold it in its place. It is lined inside by a con- 
tinuation of the same membrane as that of the chambers 
of the head. The vocal cords which come into play when 
the animal is whinnying are found along the inside of 
this cavity. These cords are not nearly so well marked 
as in the human being, and if they or the cartilage of 
the larynx become affected it generally gives rise to 
the disease called wind-broken or roaring. 

Trachea (Windpipe). — This is a tube which con- 
veys the air down from the larynx to the bronchial tubes 
in the lungs. It is made up of forty or fifty rings of 
cartilage which are united to each other by strong elas- 
tic ligaments. They give to the windpipe its flexibility, 
that is, the power to bend in any direction almost like a 
piece of elastic. From the larynx the windpipe enters 
the chest where it terminates into two small tubes, one 
going to the right lung and one to the left. These are 
called the bronchial tubes. 

Bronchial Tubes and Air Cells. — These are 
made up of the same material as that of the windpipe, 
but are only about half the size. After passing into the 



54 VETERINAEY ANATOMY 

substance of the lungs they break up into small tubes 
which pass all through the lungs and terminates into 
what is known as the air-cells. These small tubes and 
air cells are lined inside by a very thin mucous mem- 
brane, a continuation of the membrane lining the other 
organs already mentioned. Just inside this thin mucous 
membrane is found the capillary network of the lungs, 
and while the blood is slowly passing through this net- 
work of vessels it gives off to the air in the air cells car- 
bonic acid gas and takes in the oxygen from the pure air 
while it is in the lungs. 

Lungs. — Lungs are the most important organs of 
respiration. They are spongy, yellowish organs, two 
in number, one situated on the right side, and the other 
on the left. The right lung is the largest because of the 
left one having a hollow in its side for the heart. The 
lungs are separated by a partition known as the medias- 
tinum, by the heart which is in the folds of this partition, 
and also the large blood vessels and oesophagus. They 
are made up of light elastic tissue and are full of air cells 
and tubes. While the animal is alive they are very large 
and fill up nearly the whole chest cavity, but after death 
they collapse and are not nearly so large. Between the 
lungs and the ribs is found a serous membrane called 
the pleura or the lining membrane of the chest. It is 
made up of two folds, one being attached around the 
outer surface of the lungs, while the other is attached to 
the ends of the ribs at the side and at the back to the 
large curtain which separates the lungs from the bowels. 
The little glands situated in this membrane secrete an 
oily fluid which serves to lubricate these parts while the 
lungs are working in the chest so as not to cause friction. 
When this membrane becomes inflamed from a chill 
or injury it sets up the disease called pleurisy. 

Respiration. — ^^The number of respirations per min- 



SPLANCHNOLOGY 55 

ute varies with the different classes of animals ; as a rule, 
the larger the animal the slower the respiration. 

The horse 8 to 10 

Cattle 12 to 15 

Sheep and goats 12 to 20 

The dog 15 to 20 

Swine 10 to 15 

The rate of breathing is increased from the process 
of digestion immediately after eating, or may increase 
from exercise. 

RESPIRATORY SYSTEM OF THE OX. 

The nostrils are narrow and capable of little dila- 
tion compared to those of the horse. The nasal cham- 
bers differ chiefly in there being an additional turbinated 
bone. The nasal chambers communicate with the mouth, 
therefore cattle can breathe through the mouth to a cer- 
tain extent. The larynx is simpler in construction, the 
true vocal cords being only slightly developed. The 
trachea or windpipe presents no important variation. 
We may note the presence of a third bronchus, which 
passes to the right lung to supply a lobe which is want- 
ing in the horse. 

The Thoracic Cavity is relatively smaller in the rum- 
inants, and the pleurae present a ver}^^ important devia- 
tion from the arrangement found in the solipede — viz., 
the back or posterior mediastinum is imperforate and 
strong, completely separating one pleural sac from the 
other. This arrangement exists in all the domesticated 
mammals but the solipede. The left lung is divided into 
two lobes, the right into four, the front one recuin^- 
ing over and almost covering the front of the 
heart. The interlobular or cellular tissue is exceedingly 
thick, the separation between the lobules being distinctly 
visible. This arrangement explains perfectly the special 
nature of pneumonic lesions in the large ruminants. 



56 VETERINARY ANATOMY 



URINARY SYSTEM OF THE HORSE. 

The organs of this system secrete the urine from the 
blood, and excrete or expel it from the body. These 
organs are chiefly the kidneys, ureters, bladder and 
urethra. The urine, which is a watery fluid, is secreted 
by the kidneys, and carried off by their ducts, the ureters, 
to a special reservoir, the bladder, where it accumulates 
and from which it is finally expelled at intervals through 
the urethra. 

The kidneys are two compound tubular glands, one 
on the right side and one on the left side, and are sit- 
uated just below the small of the back (sublumbar 
region), the right one being the fartherest ahead. In 
shape they are long and narrow and resemble the liver 
in color. In cutting one of the kidneys open, it is found 
to be full of glands and tubes, which secrete the urine 
from the blood while it is passing through the kidneys. 
These tubes pass to the center of the kidneys, where 
they empty the urine into what is called the pelvis. The 
glands are largely supplied with blood vessels and 
nerves. The use of the kidneys are to secrete the urine 
from the blood, which contains a large amount of what 
is known as ureaic acid, and if not taken out of the 
blood by these glands, acts as a poison to the system. 

The Ureters are tubes which carry the urine down 
from the pelvis of the kidney to the bladder. They are 
two in number, one situated on the right side of the 
pelvic cavity and the other on the left side, close to the 
walls — they enter on each side at the upper surface of 
the bladder. They are only about one-sixteenth of an 
inch in diameter. 

The Bladder is situated in the pelvic cavity. When 
it is full it sometimes stretches out into the abdominal 
cavity. It consists of a body and neck. The body is 
the large part, and is placed in front; the neck being at 
the back part of the bladder. This is where the urine 
passes out of the bladder. The bladder is made up of 



SPLANCHNOLOGY 57 

three coats, somewhat similar to that of the bowels. The 
serous coat is a continuation of the serous coat found 
in the abdominal cavity lining the bowels. The inside is 
lined with mucous membrane which is thrown into folds 
when the bladder is empty. Another coat is found be- 
tween the two membranes above mentioned, called the 
muscular coat, the action of which is to contract the 
bladder when the animal wants to urinate. The bladder 
is held in by ligaments. The rectum lies above the 
bladder, which in the horse rests on the floor of the pelvic 
cavity. Its position in the mare differs from that of the 
horse. Instead of the rectum or back bowel being im- 
mediately above it, as in the horse, the womb is just 
above the bladder or between it and the rectum. The 
bladder acts as a reservoir in which to store the urine 
until it is full; it then presses on the walls and nerves, 
giving a peculiar sensation to these parts, causing the 
walls to contract, forcing the urine into a tube which 
carries it from the body. This is called the urethra. 
The neck of the bladder is simply an opening at the 
back part, and is guarded by a valve which prevents the 
urine from dripping out except when the animal is pass- 
ing its urine or water. 

The Urethra is the tube which carries the urine from 
the bladder out of the body. It is situated much differ- 
ently in the mare than in the horse. In the mare it is 
very short, passing from the neck of the bladder along 
below the womb and vagina, which is the passage from 
the outside into the neck of the womb. It opens up into 
the underside of this passage about four inches in from 
the outside. This opening is guarded by a small, thin 
valve, and can be felt by passing the finger along the 
under side of the passage which leads into the womb. 
In the horse this tube is a great deal longer than in the 
mare. It commences at the bladder, passes along below 
the rectum or back bowel to just below the anus. Here 
this tube bends downward and foi'ward and passes into 
the penis, continuing down to the end where it termin- 
ates. Its purpose is to carry the urine from the bladder 



58 VETERINARY ANATOMY 

out of the body and to perform certain actions in con- 
nection with the genital organs. Its hning is a continua- 
tion of the membrane of the bladder. 

URINARY ORGANS OF THE OX. 

The chief difference in these organs occurs in the 
kidneys, which in the ox are larger, and in place of being 
smooth, like those of the horse, are rough, resembling a 
bunch of grapes. The bladder and the urinary organs 
resemble those of the horse. 

GENERATIVE SYSTEM OF THE HORSE. 

Animals possess the faculty of reproducing or prop- 
agating their species, and this function may be non- 
sexual or sexual, the former being confined to certain 
lowly-organized classes of animals. 

In all the higher animals the generation of a new be- 
ing is dependent upon two individuals, a male and a fe- 
male, the female furnishing a germ, or ovum, the male 
a fecundating fluid, or sperm, which animates the germ 
and renders it fit for development. 

Both the ovum of the female and the sperm of the 
male are secretions of glands, which are termed the geni- 
tal glands, male and female; and in either sex the gen- 
erative system may be said to consist of these glands, 
with certain accessory organs. The act of coition brings 
the two secretions into contact. 

We have two systems of genital organs to consider 
— the male and the female. 

Male. — The genital organs of the horse are as fol- 
lows: The scrotum or bag, the testicles, the spermatic 
cord, the vesiculae seminales or pouches which hold the 
semen or sperm, the urethra, the penis and the sheath. 

The Scrotum is a sac or bag which contains the tes- 
ticles. It is situated between the hind legs, and is cov- 



SPLANCHNOLOGY 59 

ered on the outside by a very fine, soft skin. Passing 
up in the center under the sheath the scrotum is a well 
marked line in the skin called median raphe. This can 
be plainly seen when the horse is on his back. It con- 
tinues up, gradually getting fainter until it reaches the 
anus. Under the skin are layers of white fascia or tis- 
sue which can be seen by cutting through the scrotum. 
There is a partition in the scrotum separating the two 
testicles. The size of the scrotum is affected very much 
by the weather. In cold weather its fibres contract, 
causing it to get very much smaller, while in warm 
weather the fibres relax, causing it to become very much 
larger. The scrotum contains, supports and protects 
the testicles. 

The Testicles are the glands which secrete the semen 
or sperm. They are two in number, one situated on the 
left side and the other on the right. They are oval in 
shape, and are attached above to the spermatic cord. 
Before the animal is born the testicles are situated in 
the abdominal cavity and attached to the serous mem- 
brane which has already been spoken of in connection 
with that cavity. At or about the time of birth, there 
takes place what is known as the descent of the testicles 
into the scrotum. In their downward course they pass 
through a slit or small opening at the back part of the 
muscles of the abdomen, w^here they are attached to the 
under part of the hip bone. These slits or openings are 
known as the inguinal rings. They can be felt in the 
horse by pressing the fingers well up into the groins. 
The descent of the testicles is an important point to re- 
member. If the testicle does not descend into the scro- 
tum the horse is known as a ridgling. In this case the 
testicle is not found in the scrotum. At the front part 
of the testicle there is a small ridge called the globus 
major and at the back of it is another smaller ridge 
called the globus minor. Passing between these two 
ridges is another well marked ridge called the epididy- 
mis. These can be easily seen by examining the testicle 



60 VETERINARY ANATOMY 

after the animal is altered or castrated. The substance 
of the testicle is made up of small glands and fine tubes. 

These tubes, as they pass towards the back of the 
testicle, form into larger tubes and finally unite to form 
one called the vas deferens. 

The Spermatic Cords, or the cords of the testicles, 
are attached above to the inguinal rings or openings 
mentioned before. They are about five or six inches 
long and have the testicles attached to them below. In 
each cord is found a small muscle which goes by the 
name of the spermatic muscle, the rest of the cord being 
made up of the spermatic artery, veins and nerves. 
Running up at the back of these cords is found a tube 
called the vas deferens. Around the spermatic cords 
and testicles is a serous membrane, one layer being at- 
tached to the testicle and cord, while the other is closely 
attached around the inside of the scrotum. In this mem- 
brane are small glands which secrete an oily fluid to lub- 
ricate the parts, preventing friction when they are jolted 
about in the scrotum. This fluid flies out as soon as 
the scrotum is cut. This is important, because 
sometimes from a slight injury the glands will secrete 
a large amount of this flviid, thus causing the scrotum 
to look large and swollen. This disease is known as 
hydrocele or water in the scrotum. 

Vas Deferens. — These tubes are two in number 
and are situated just behind the spermatic cords. They 
are about an eighth of an inch in diameter and quite hard. 
They carry the semen up the back part of the spermatic 
cord through the inguinal rings, before mentioned. 
They pass backward and upwards, one on each side, to 
the upper part of the bladder, where they empty into 
two small pouches or sacs, called the vasiculae seminales. 
These store up the semen as it is secreted by the testicles, 
and when full j)resent the appearance of a pear. 

Vesiculae Seminales. — These sacs or pouches are 
situated at the upper side, over the neck of the bladder, 
one on each side. The}^ have the vas deferens emptying 



SPLANCHNOLOGY 61 

into them at the front end, while at the back end of each 
is a small opening that leads out into another small tube 
which passes backward and empties into the urethra, 
mentioned before as carrying the urine out from the 
bladder. These sacs or pouches store up the semen or 
sperm of the horse. During sexual intercourse, these 
pouches contract and force the semen through the little 
tubes mentioned out into the urethra, leading down 
through the penis. 

The Penis is the main organ of sexual intercourse. 
Its substance is formed of what is known as erectile tis- 
sue, which under certain circumstances becomes enor- 
mously distended with blood. Passing up the under 
side there is, what has already been mentioned, the 
urethra, or the tube, v^diich carries the urine out of the 
body, and also in the act of intercourse carries the se- 
men. This is used for two purposes, as we have already 
mentioned. 

The Sheath is a loose process of skin which passes 
downward from the scrotum, generally from about five 
to six inches, according to the size of the animal. It is 
attached to each side, leaving a hole or opening in the 
center through which the penis passes. The outside of 
the sheath is covered by a thin, delicate skin similar to 
that of the scrotum. It is lined inside by a membrane 
containing many small glands, which secrete a thick, 
dark fluid to lubricate this passage. Sometimes this 
fluid collects in here and has the appearance of tar. This 
is important, for when it collects to a large extent the 
sheath should be washed. 

The Semen or sperm of the horse is a light fluid, 
which, w^hen examined under a microscope is found to 
contain small objects called spermatozoa. These move 
about, and ^vhen in the womb meet the ovum of the fe- 
male, which is secreted by a gland called the ovary. 
When these two small objects unite, they form the 
foetus, or what may be called the animal in its first stage 
of development. 



62 VETERINARY ANATOMY 



FEMALE GENITAL ORGANS. 

The female genital organs, or the organs of the mare, 
are very much different from those of the horse. They 
are known as follows : The ovaries, the fallopian tubes, 
or tubes which carry the ovum from the ovaries to the 
uterus or womb, the uterus or womb, the vagina, and the 
vulva. 

The Ovaries in the mare correspond to the testicles 
in the horse. Each is about the size of a pigeon's egg, 
and resembles it much in shape. They are held in place 
by ligaments, and at the back part are provided with 
tubes leading from them called the fallopian tubes. The 
ovaries secrete the ovum or germ. This is a very minute 
body, which, when examined under the microscope, is 
found to be only 1-150 of an inch in diameter. 

The Fallopian Tubes are two canals, one on each 
side. They pass backward and upward, and enter the 
front part of the uterus or womb. These small tubes 
are simply used to carry the germ or ovum up from the 
ovaries and empty into the uterus or womb. 

The Uterus or Womb is a muscular sac situated in 
the pelvic eavity, bounded above by the rectum, below 
b}^ the bladder, and on either side by the walls of the 
pelvic cavity. It is divided into what is known as a body 
and a neck. The body of the womb is very small, being 
only about four to six inches in length and a couple of 
inches in diameter when the animal is not pregnant. 
Near the front end, at the upper side there are openings 
by which the ovum enters. When the animal becomes 
pregnant, the body of the womb becomes enlarged and 
passes forward and to the left side of the abdominal 
cavit3^ It continues to enlarge as the time of pregnancy 
passes on, until the foetus, or young, has attained its 
full size. After the mare has had her young, the womb 
begins to get smaller until it attains its natural size 
again. The womb is very largely supplied with blood 
vessels and nerves. This is especially so when the ani- 



SPLANCHNOLOGY 63 

mal is pregnant, as it takes a large amount of blood to 
nourish the foetus, or the young animal, before birth. It 
is made up of three coats. The inner is called mucous 
membrane, and in the mare, while pregnant, is covered 
with numerous processes about the size of peas to which 
the placenta or after-birth of the foal is attached. The 
muscular coat is next to that of the mucous coat, and lies 
between the outer and inner coats of the womb. It is 
made up of muscular fibres, and is strong and thick in 
the womb, much thicker than it is in the bowels or other 
organs, already mentioned. This coat supports and pro- 
tects the foetus, or young, while being carried in the 
womb, and at the time of parturition, or what is com- 
monly known as foaling, this coat also comes in use. 
It contracts the womb very forcibly on the foal, while 
the neck of the womb lies open, thus helping to force 
the foal out of the womb. This is important as the con- 
traction of this coat produces what is known as labor 
pains. Lying outside, and covering around the womb, 
is a serous coat, a continuation of the serous coat of the 
bowels. The womb is held in place by strong ligaments 
attached to the sides, and from there to the hip bones. 
These are called broad ligaments. At the back part of 
the womb is the neck. It consists of an opening, formed 
by a projection about the size of an egg. This has a 
hard, gritty feeling when the animal is not in season. 
The neck at this time is closed. The neck of the womb 
is under control of the muscle around it, and this muscle 
is under control of the nerves of the womb. When a 
mare comes in season this muscle is relaxed to a certain 
extent, thus allowing the neck to open wide enough for 
the passage of a couple of fingers. By working around 
it with the fingers at this period it can be forced wide 
enough to admit a man's hand. If the mare is put to the 
horse at this time and becomes pregnant or with foal, 
the muscles in the neck of the womb contract, firmly 
closing it. It remains closed until the time of foaling. 
When, at the time of foaling, the labor pains come on, 
the muscle in the neck dilates, allowing the neck of the 



64 VETERINARY ANATOMY 

womb to open large enough for the foal to pass out. The 
neck of the womb can be felt easily by oiling the hand 
and passing it into the passage of the womb. It will be 
noticed, too, that the neck spoken of projects into the 
passage. 

The Vagina and the Vulva. — These two organs 
together make up the passage which leads into the womb 
from the outside. In the young mare they are separated 
by a thin curtain, or partition, made up of mucous mem- 
brane. This curtain is found about four inches from the 
outside, and is known as the hymen. It is destroyed, or 
should be, when the mare is first put to the horse, al- 
though it is broken down other ways, and in some cases 
it will disappear of its own accord. The part of the pas- 
sage in front of the hj^men is called the vagina. This 
passage, in structures, resembles the womb, but is not 
so strong. There are numerous glands situated along 
the inner lining which secretes a fluid to lubricate it. The 
principle use of this organ is to guide the penis during 
sexual intercourse, and at the time of foaling serves as 
a passage for the foal. That part of the passage be- 
hind the hymen is known as the vulva. It is about four 
inches long and about two or three inches high, varying 
according to the size of the mare. In front, it is sep- 
arated from the vagina by the hymen membrane. It 
resembles the vagina in structure and is also provided 
with little glands in its inner membrane to secrete fluid 
to lubricate the passage. At the back part of the Aailva 
or around the outside is what is known as the lips of the 
vulva, one on each side of the opening. The outside of 
the lips is covered by a veiy fine skin. Just below the 
skin, they consist of erectile tissue, v^hich is the same 
kind of tissue as that of the penis of the horse. This 
tissue is found more abundantly in the lips of the vulva 
of the young mare than in those of an old mare. The 
opening between these lips is situated just below the 
anus, or the opening where the back bowel ends. At 
the back part of the vulva, on the under side, is an open- 
ing, or hole, about large enough for the passage of a 



SPLANCHNOLOGY 65 

man's finger. Through this hole the tube leading from 
the bladder enters into the passage and allows the urine 
to pass into the vulva, through which it runs out of the 
body. The clitoris is situated on the upper side of this 
passage, just inside the lips. It can be seen in the mare 
when she works the vulva after passing urine. Just be- 
low the clitoris are found two or three small glands 
which secrete the fluid that passes away when the mare 
is horsing. 

Mammary Glands, or what is known as the mare's 
udder or bag, are two in number, situated between the 
thighs. In the young mare they are very small, but 
after the mare is pregnant a few months these glands 
enlarge, until at foaling time they attain their largest 
size. They are covered outside by a thin, smooth skin. 
The substance of them consists of small glands and 
tubes retain or hold milk until it is drawn away from the 
bag either by milking or by the young animals sucking. 
During the time of suckling the young, the glands are 
largely supplied with blood, from which the milk is se- 
creted. On the under side of each gland is found the 
teat, or that part taken hold of by the young when suck- 
ing. The end of the teat is pierced by several small 
holes, through which the milk passes. 

GENITAL ORGANS OF THE BULL. 

The testicles are ovoid in shape and well developed, 
its long axis being nearly vertical ; the membrane which 
separate the two testicles is very strong. 

The spermatic cord and artery are small compared 
with those of the horse. 

The penis is long and pointed, and has an S-shaped 
curve in it just below the pelvic bones; this curve can be 
felt by feeling just behind the bag. 

The sheath is long and runs further forward on the 
belly. It has a tuft of hair on the point of it. During 
the time the bull is serving the S-shaped part of the penis 



66 VETERINAUY ANATOMY 

is straightened out by the action of the protracters mus- 
cles, and drawn back into the S -shaped curve by retractor 
muscles. 

The urethra is completely enveloped by the fibrous 
sheath. 

GENITAL ORGANS OF THE COW. 

The ovaries of the cow are comparatively smaller 
than those of the mare, but resemble them in structure. 

The uterus or womb of the cow somewhat resembles 
that of the mare, but the inner membrane is different, 
being covered with sixty or eighty mushroom-like bodies 
about the size of a pigeon's egg, more flattened out. 
These bodies receive the name of cotyledons ; to these the 
placenta or afterbirth is attached — a very important 
point with which every person interested should be fa- 
miliar. These may be felt by examining a cow soon after 
calving. The passage from the womb of the cow is 
shorter than that of the mare, but is formed on the same 
principles. 

The mammary glands constitute an organ termed 
the udder, which is composed of two symmetrical halves, 
placed one against the other. Each half is again divided 
into two distinct glands, each with its own teat, so that 
the udder consists of four mammae and four teats; be- 
hind this there may be two small rudimentary teats. In 
the center of each quarter, just at the base of the teat, is 
a large cavity, the general receptacle of all the milk 
ducts. From this cavity, which is sometimes large 
enough to contain a quart, proceeds down the center of 
the teat one defined canal from which the milk is drawn. 

In the small ruminants as the sheep and goat there 
are two mammae and two teats, constructed like those of 
the cow. 



CHAPTER V. 
ANGIOLOGY. 

Blood- Vascular System of the Horse. 

Under this heading we describe the organs of circu- 
lation, by the action of which certain fluids are propelled 
through the body. It is customary to divide this branch 
of the subject into two sections, considering respectively 
the blood-vascular and lymphatic systems. 

Blood-Vascular System. — This involves the con- 
sideration of the blood, a fluid which supplies nutriment 
to the tissues and receives effete material from them ; the 
heart, a muscular organ which, by its contraction, initi- 
ates the motion of the blood ; the arteries, a series of tubes 
which convey the blood from the heart to all parts of the 
body; the veins, tubes which return that fluid to the 
heart; and the capillaries, minute tubes joining the small 
arteries and veins. 

Blood. — Blood is a fluid tissue, which nourishes all 
living structures, being the medium by which nutritive 
material is conveyed to, and effete or waste material con- 
veyed away from the solid tissues. It is an opaque, thick- 
ish, clammy liquid, with a peculiar odor, sickly saline 
taste, and alkaline reaction. Its color varies in different 
parts of the same animal, that in the arteries being bright 
red or scarlet, while the blood in the veins is of a dark 
purplish hue. 

When examined microscopically, the blood is found 
to consist of minute corpuscles, and a clear, transparent, 
yellow fluid, the liquor sanguinis, or plasma, in which 
the eorpuscles float. The corpuscles are of two kinds, 
the red and the white or colorless; the former, by far 
more numerous, vary in proportion. Red corpuscles vary 
in shape, but in all mammals ' ( animals that suckle their 

67 



68 VETERINARY ANATOMY 

young) are more or less flat, the families excepted where 
they are oval, as in birds, reptiles, and fish, which 
are also nucleated. Their average diameter in the 
horse, ox or sheep is about l-4000th part of an inch, their 
average thickness being about one-fourth of this. Each 
surface is depressed towards its center, hence the cor- 
puscle is appropriately described as a bi-concaved disc. 

The white corpuscles are larger than the red, round 
in shape, and nucleated. 

The liquor sanguinis is pale and clear, and consists 
of water, fibrin, albumen, fatty compounds, extracts, 
odoriferous and saline matters. The serum is a thin, 
transparent liquid, of a pale-straw or yellow color, con- 
sisting of the liquor sanguinis deprived of fibrin. It con- 
tains nearly 90 per cent of water, is always slightly alka- 
line, and coagulates when heated, owing to the large 
quantity of albumen it contains. Fibrin is a white, 
string}^ elastic substance, which, when the blood is in cir- 
culation, is in solution, and cannot be distinguished from 
the other constituents of the plasma. 

Heart. — The heart is the principal organ of circula- 
tion ; it weighs about six and one-half pounds in the aver- 
age horse and acts as a force pump to force the blood 
through the arteries. It is composed of strong muscular 
tissue, which acts involuntarily, and is situated between 
the lungs, which are divided by what is known as the 
mediastinum. This is a division between the lungs made 
up of two folds, the heart being between them. The bot- 
tom or apex, of the heart is downward and rests just 
above the breast-bone ; the upper part, or base is directed 
upward and to the left side, the left lung having a de- 
pression on its inner surface for the heart to work in. 
There is a covering or sack around the heart which helps 
to protect and support it in its place. It is attached 
above to the back-bone, and below to the bones of the 
breast. This sack is made up of fibrous tissue and is of a 
whitish appearance; inner surface is smooth, and sup- 
plied with numerous small glands which secrete an oily 




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EXPLANATION OF PLATE V 

Blood- Vascular System of the Horse 



1. 


Heart, right ventricle. 


18. 


2. 


Heart, left ventricle. 


19. 


3. 


Heart, left auricle. 


20. 


4. 


Pulmonary artery. 


21. 


5. 


Pulmonary veins. 


22. 


6. 


Anterior aorta. 


23. 


7. 


Carotid artery. 


23'. 


8, 


, Glosso-facial artery. 


24. 


9. 


Left brachial artery. 


25. 


10. 


Dorsal artery. 


26. 


11. 


Superior cervical artery. 


27. 


12. 


Vertebral artery. 


28. 


12' 


. Internal thoracic artery. 


28'. 


13. 


Humeral artery. 


28" 


14. 


Radial artery. 


29. 


14'. 


, Cubital artery. 


30. 


15. 


Great metacarpal artery. 


31. 


16. 


Ungual branches. 


32. 


17. 


Posterior aorta. 


33. 



Coeliac axis. 
Mesenteric arteries. 
Renal artery (left). 
Small testicular artery. 
Posterior vena cava. 
Portal vein. 
, Hepatic circulation. 
External iliac artery. 
Internal iliac artery. 
Lateral sacral artery. 
Femoral artery. 
Posterior tibial artery. 
Anterior tibial artery. 
.Fermoro-popliteal artery. 
Metatarsal vessels. 
Venous plexus of the foot. 
Internal saphenic vein. 
Cephalic vein. 
Jugular vein. 



69 



70 VETERINARY ANATOMY 

substance called serous fluid. This lubricates the outer 
surface of the heart and the inner surface of the sack so 
that in action it does not irritate the walls or surfaces. 
The cavity of the heart is divided into two parts, the 
right and left sides; each of these parts is again subdi- 
vided. The upper cavity is called auricle and the lower 
cavity ventricle ; thus there are the right and left ventri- 
cle and right and left auricle. The right auricle com- 
municates with the right ventricle by an opening in the 
septum or partition on the right side of the heart. This 
opening is guarded by a valve to keep the blood from 
flowing back into the auricle. The left auricle commu- 
nicates with the left ventricle, same as on the right side. 
The right side of the heart is sometimes called the venous 
side and contains only venous or impure blood. The 
left side is sometimes called the arterial side. It contains 
pure blood only. This side of the heart is very much 
stronger and thicker than the right side. 

Arteries — Arteries are tubes the purpose of which 
is to convey the blood from the heart. For this reason it 
is apparent that all arteries carry pure arterial blood with 
but one exception. The pulmonaiy artery carries the 
blood from the right ventricle to the lungs, and conse- 
quently carries impure or venous blood. Each time the 
left ventricle contracts it causes a wave, as it were, to pass 
all through the arteries. This contraction takes place 
when in a healthy condition about 36 to 42 times every 
minute and gives rise to what is known as the pulse. This 
wave, or beating, may be detected at any point where the 
artery is situated so closely to the surface as to affect the 
outside of the body sufficient to be felt by placing the 
finger on the point; consequently the pulse may be 
counted at any of these points. Place your forefinger on 
the lower edge of your own lower jaw directly under the 
corner of your mouth. At this point an artery passes 
out over the jaw bone and therefore runs very close to 
the surface, making it quite possible to feel the wave 
caused by the contraction of your own heart, quite dis- 



ANGIOLOGY 71 

tinctly. Near this point on the jaw of the horse the pvilse 
is most conveniently felt and counted. 

The walls of the arteries are composed of elastic tis- 
sue and after death are always lying open. Blood is 
never found in them after death because they continue 
to contract sufficiently long enough to force all the blood 
through them. 

Veins. — Veins are tubes in construction not so 
strong as the arteries — the purpose of which is to convey 
the blood from all parts of the body to the heart. The 
heart wave does not affect the veins, and consequently 
the pulse cannot be detected by placing the finger on an 
exposed portion of one of them. It is also apparent that 
all veins carry impure or venous blood with but one ex- 
ception, viz., the pulmonary vein, the purpose of which 
is to conduct the purified blood from the lungs to the 
heart. 

Capillaries. — The small arteries terminate in a sys- 
tem of minute vessels — the capillaries — which are inter- 
posed between the termination of the arteries and the 
commencement of the veins, forming plexuses (network) 
which vary much in arrangement. Their average diam- 
eter is about 2/lOOOths of an inch, varying in different 
construction of the organs, smallest in the brain and mu- 
cous membrane of the intestines, larger in the skin, in 
glands, and the interior of bones. All arteries do not 
terminate in capillaries, an exception being in erectile 
tissue of the penis, where arteries end in cells or cavities 
placed at the origin of the veins. As the blood passes 
slowly through these capillaries, the nourishment is ab- 
sorbed from it through their very thin walls to supply the 
tissues of the body. When the blood passes through this 
capillary network it again enters into large vessels called 
the veins, which carry it on its way back to the heart. 

Course of the Blood. — We have seen that the 
heart is divided into a right or venous, and a left or ar- 
terial portion. The blood is pumped b}^ the heart to all 
parts of the body, through the arteries, passing through 



72 VETERINAEY ANATOMY 

the capillary system, where it parts with its nourishment, 
is collected and returned to the heart by the veins, is again 
pumped by the heart to the lungs, where it is purified 
and returned to the heart to again commence the circuit 
as before. 

Lymphatic System. — The lymphatic or absorbent 
system is closely connected with the blood-vascular sys- 
tem, and is made up of very fine minute tubes and glands. 
These convey from the tissues of the body a clear fluid 
known as lymph, and pours it into the blood of the veins 
as it is on its way back to the heart. These glands are 
found all through the body; for instance, there is a large 
group inside the thigh or stifle joint of the horse, and an- 
other large group inside the shoulder. It is important 
to note these, as they sometimes become inflamed and the 
leg is swollen. They are then the seat of the disease 
called weed in the leg, or lymphangitis. 




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CHAPTER VI. 

NEUROLOGY. 

This illustration shows where the brain, spinal canal 
and the principal nerves of the horse are located. 

Study of the Nerves. — The nervous system is a 
very important set of organs controlling the motion of 
the various members of the body and supplying the dif- 
ferent senses of feeling, seeing, hearing, smelling and 
tasting. The two principal organs of the nervous system 
are the brain and spinal cord. 

The brain is the center of the whole nervous system, 
and is situated in the cranial cavity, surrounded by three 
delicate membranes, the outer one being attached to the 
inner wall of the bones forming the brain cavity. The 
brain contains several important nerves called cranial 
nerves, which are given off from the brain and pass down 
through the various foramen or openings in the head to 
supply the different organs situated there. The optic 
nerve passes down to the eye, giving the sense of sight. 
The auditory nerve passes down to the drum of the ear 
to give the sense of hearing. The olfactory nerves, which 
give the sense of smell, are situated in the mucous mem- 
brane lining the nose. The nerves passing down to the 
tongue give the sense of taste. Other nerves pass down 
to the lips, teeth, mouth and face, giving motion and feel- 
ing to the parts mentioned. Others pass down to the 
pharynx or gullet, giving it the power of swallowing. 

The spinal cord passes from the brain through the 
openings in the bones of the back, which gives off nu- 
merous small nerves that supply the muscles of the back 
with motion and feeling. Nearly opposite the shoulder 
blade the spinal cord gives off a large trunk of nerves, 
portion of which supplies the heart and lungs with nerv- 



73 



74 VETERINARY ANATOMY 

ous power. This is a point of importance, for if the spinal 
cord becomes injured in front of these nerves immediate 
death is the result. The other portions of this trunk of 
nerves supply the shoulder, chest and muscles of the front 
legs. Passing backward along the spinal cord is found 
the sympathetic system of nei'ves, which go to supply 
the bowels, stomach, liver, kidneys, and other organs sit- 
uated in the abdominal cavity. Coming backwards along 
the spinal cord to about oposite the hip bones, is another 
set of nerves, one of which goes to supply the rectum, 
or back bowels. Others go to the generative and urinary 
organs where they assist in performing their functions. 
Other nerves pass to the small organs situated in the pel- 
vic cavity; some of these nerves pass down to the hind 
legs, supplying them with nervous power. The re- 
mainder of the nerves go to supply the tail. 

The difference between the nervous system of a horse 
and other animals is not worth mentioning. 



CHAPTER VII. 
AESTHESIOLOGY. 

The study of organs of special sense, the ear, eye and 
organs of special sensation, skin, hair, foot, etc. 

THE EAR. 

The apparatus of hearing is composed of three parts 
the outer, middle, and inner ear; the two first being ac- 
cessory for the collection and transmission of sounds, and 
the latter the essential organ which receives the impres- 
sions thus conveyed. 

The inner part, or drum, of the ear, is situated in the 
hardest bone of the body, called the petrosal. The nerve 
which passes into the drum of the ear and gives the sense 
of hearing, is called the auditor}^ nein^e. From the drum 
a small opening passes out into the outer part of the 
ear; this is the portion which is seen on top of the head. 
It is made up of a membrane known as the cartilage, 
which gives the ear its stiffness. This cartilage is covered 
by a fine, delicate skin, covered on the outside by fine, 
short hair. Situated on the inner side of the outer ear 
are numerous long hairs projecting outward, the use of 
which is to keep foreign bodies from dropping into the 
ear. The ear is moved backward and forward by small 
muscles which are attached around it. 

THE EYE. 

The apparatus of vision comprises the essential 
organ, the globe of the eye or eyeball, and its ac- 
cessory parts or appendages. The eyeball is situated 
in the orbital fossa, mentioned in chapter on the bones of 
the head. It is chiefly made up of several coats around 

75 



76 VETERINARY ANATOMY 

the outside, and in the center by the humours of the eye. 
On the inner side of these coats is a thin membrane called 
the retina, which contains the branches of the optic nerve. 
This receives the reflections of objects as they pass 
through the humours of the eye and from which the sen- 
sation passes along the optic nerve to the brain. The ob- 
long opening seen in the middle of the eye is known as 
the pupil. If a horse be led from a dark stall into the 
light and the pupils of the eyes watched closely, it will 
be noticed that they get smaller, but on returning it to 
the stall the pupils will be noticed to dilate or get larger ; 
thus it is seen that the pupils do not always remain the 
same size. The chief use of the pupil is to gauge the 
sight. At the back part of the eye are several muscles at- 
tached from around the eye to the bones in the fossa. 
These muscles move the eye and assist in holding it to its 
place. Around the front part are two movable curtains, 
one above and the other below, called eyelids, the use of 
which is to open and close the eye, and also to protect it 
from injuries. Around the free border of the eyelids are 
what is known as the eyelashes, which keep foreign sub- 
stances from falling into the eye. Situated in the inner 
angle is what is known as the haw of the eye ; this mem- 
brane also helps to protect it. In the corner of this 
angle is a small duct or opening, through which a fluid 
called the tears passes down into the nasal tubes, from 
whence it is carried down through the bones of the head 
and emptied into the under part of the nostril or nose. 
A small gland is situated on the upper part of the eye. 
This gland secretes the tears which lubricates the eyes. 
The color of the eye is generally brown, but in some cases 
it is white. It is then called a moon eye. 

THE SKIN. 

The skin is a membrane or external casing of the 
body. The skin itself consists of two layers covered 
with hair, fine or coarse, long or short, according to its 
position or purpose which nature intended it to serve. 



AESTHESIOLOGY 77 

The outer layer is called the epidermis, the inner the 
dermis. 

The Epidermis. — The epidermis is the outer layer. 
It is not supplied with nerves and blood vessels, its pur- 
pose being to protect the inner layer. This layer under- 
goes a continual process of being made up and passing 
away in dandruff. 

The Dermis. — The dermis or true skin lies under 
the epidermis. It is well supplied with nerves and blood 
vessels, part of the nerves being the nerves of touch. 
This fact accounts for its becoming so very sensitive and 
painful when through injury of any kind the outer layer 
is scraped off. It is attached to the body by a layer of 
white tissue known as the areolor tissue, this being that 
which is cut through when the animal is being skinned. 
The thickness of the skin varies in different parts of the 
body, being thinnest in the under parts. The sweat 
glands are situated in the dermis. 

THE HAIR. 

There are three kinds of hair on the horse — the com- 
mon, the finest of the three, covers most of the body ; that 
of the mane and tail, coarse and long; and that growing 
on the muzzle or nose and lips, long and usually black, 
known as tactile or cat hairs. 

On the inside of the front legs, just above the knee, 
and on the inside of the hind legs, above the hock, are 
rough, horny spots. These are called chestnuts. 



78 VETERINARY ANATOMY 

EXPLANATION OF PLATE VII 

Anatomy of the Foot. — This illustration repre- 
sents the foot of a horse sawed from above the fetlock 
down through the center of the foot. It shows the struc- 
ture of the foot, the name of each j)art being given ac- 
cording to number. 

1. Lower end of large metacarpal, or cannon bone. 

2. Bursa, which secretes the joint oil that lubricates 
the place where the tendon, or cord, on the front of the 
leg passes down over the front of the fetlock joint. This 
is important as it sometimes gets injured and becomes 
enlarged. It is then called a bursal enlargement, and is 
of the same nature as a wind gall. 

3. Fetlock joint. 

4. Os suffraginis, or large pastern bone. 

5. Pastern joint. This joint is important; when 
diseased it is the seat of a high ringbone. 

6. Os coronae or small pastern bone 

7. Coffin joint. This joint is important, for when 
it is diseased it is known as a low ringbone. 

8. Wall of the hoof. 

9. Os pedis, or coffin bone. 

10. Sensitive wall, or quick of the foot. 

11. Sensitive sole, or quick of the foot. 

12. Frog of the foot, or horney frog. 

13. Planter cusion, or fatty frog. 

14. Navicular bone. This is also important, for 
when diseased it is the seat of navicular, or coffin joint 
lameness. 

15. Back tendons below the fetlock. 

16. Sesamoid, or feltock bones. 

17. Skin. 

18. Back tendons above the fetlock. 

Foot. — In equine anatomy the word "foot" implies 
the hoof, together with the bones and soft structures con- 



PLATE VII. 




CROSS SECTION OF THE FOOT OF THE HORSE. 



AESTHESIOLOGY 79 

tained therein. Many of these objects have already been 
described, so that our description here will be confined 
almost to the hoof and the structures with which it comes 
into immediate contact internally. 

Wall of the Foot. — The wall is that part of the 
hoof seen when the foot is resting flat on the ground. 
It is divided into the toe, the quarters, the heels and the 
bars. The toe forms the front, and is the thickest and 
strongest part of the wall. The quarters are situated 
at the side. The walls are not nearly so thick here as at 
the toe, but are almost straight up and down. The heels 
are situated at the back part of the foot. From the heel 
is a process of hoof, which looks like a bar, passing for- 
ward between the frog and the sole of the foot ; this can 
be seen plainly by raising up the foot. There is one of 
these at each side of the frog. They act as braces to 
the heel and the quarters of the wall ; these are called the 
bars. Covering the outside of the wall is a fine mem- 
brane called the periople, which gives the hoof its pol- 
ished appearance. This can be seen best when the hoof 
is well washed off, as it is after traveling through wet 
grass. This membrane keeps the moisture in the hoof 
and protects it from water. This is a point of impor- 
tance in shoeing horses, as it is very injurious to file the 
wall too much. Around the top part of the wall, where 
it unites with the skin, is a groove w^hich contains a white 
band, called the coronary substance, or band. This 
nourishes the wall of the hoof, or, in other words, it is 
from this that the wall of the hoof grows. The under 
part of the wall, or that which rests on the ground in the 
unshod animal, is called the spread of the foot. On the 
inside of the wall, attaching it to the bone of the foot 
called the os pedis, is the part called the quick, or sensitive 
laminae. It is important to note this when driving nails 
in shoeing. The nail should not be driven into this mem- 
brane, nor should it be even pressed upon, for it is very 
sensitive. When a nail has been driven so as to injure 
the membrane it is a common expression to say, "You 
have pricked that horse's foot." 



80 VETERINARY ANATOMY 

Sole of the Foot. — The sole is a thick plate of horn 
which helps to form the under part of the hoof. It is situ- 
ated between the inner border of the under part of the wall 
already mentioned and the front of the frog. The under 
part of the sole is concave, or hollowed out. The upper 
part of the sole is attached to the under surface of the 
OS pedis bone, or bone of the foot, by a membrane called 
the quick, or sensitive sole — this membrane is merely a 
continuation of the sensitive laminae. The outer part 
of the sole is attached to the inner part of the wall. When 
pared down a white ring is seen Where the sole and the 
wall unite. At the back part of the sole there is a notch 
the shape of the letter V; in this notch the frog is sit- 
uated. It is important to remember when shoeing never 
to let the shoe rest on any part of the sole; neither is it 
well to pare off too much of the barky-looking substance 
of the sole, as this helps to keep the moisture in the foot. 
When this is taken off it allows the moisture to escape 
and the hoof becomes dry and contracted. 

Frog of the Foot. — The frog is the important 
spongy horn found in the V-shaped notch in the back of 
the sole. It is wide at the back and helps to form the heel 
of the foot; the pointed part in front is called the apex 
of the frog. The under part of the frog is triangular in 
shape and has a hollow in it called the cleft of the frog. 
There is a hollow at each side of the frog, between it and 
the bars, called the commissures of the frog. On the up- 
per part is a membrane, known as the sensitive frog, 
which attaches it to the under part of the os pedis, or foot 
bone. This membrane is simply a continuation of the 
sensitive sole spoken of in connection with the sole. The 
back part of the frog is the widest part and spreads out 
to form the heel. 

The study of the foot of the horse is of the greatest 
practical importance, owing to the many diseases and 
injuries to which it is liable. It resolves itself here into 
the consideration of the hoof or horny case, and the parts 
contained within it. 



CHAPTER VIII. 
EMBRYOLOGY. 

The Development of the Young. — We must here 
first speak of the ovum or germ, which is secreted by 
the ovary of the mare. Every time she comes in season 
(which occurs every three weeks during the hot weather) 
this ovum passes down the tubes before the womb as be- 
fore mentioned, where it remains a few days and then 
dies if she is not put to the horse ; but if, during tlie time 
this ovum is in the womb she is put to the horse and one 
of the spermatozoa from the semen of the horse comes 
in contact with it (the ovum) and a union of these takes 
place, then the rest of the semen dies and passes away, 
and the neck of the womb contracts gradually until it is 
perfectly tight. These two little bodies begin to grow 
when united and form the foetus, or foal. The foetus 
may be for convenience divided into three parts, viz.: 
the foetus proper, the navel string, and the placenta. 
The placenta is the part which is found covering the foal 
and is attached to the little pea-like elevations on the in- 
side of the womb. This covering is found to be full of 
small blood vessels which finally unite to form two larger 
vessels, known as the navel veins. These carry the blood 
up through the navel opening of the foal and then to its 
heart. By the action of the heart it is forced all through 
the body of the foal and returned again to the heart. It 
is then forced down another artery to the navel opening, 
along the navel cord, into the placenta again, where it is 
distributed through the small blood vessels. When the 
blood comes down this cord from the foal it is in its 
impure state, and while it is passing through 
these small vessels in the placenta it comes very 
close to the small blood vessels in the womb. The 
blood is cleansed and nourished from the blood of its 



81 



82 VETERINARY ANATOMY 

mother by a process similar to that which was spoken of 
when discribing the lungs. The foetus, or foal, does 
not grow so fast the first month as it does later on. At 
the age of seventeen weeks the first hair appears on the 
lips and the tip of the tail. Between the thirty-fifth and 
the fortieth week the foal begins to show signs of life, 
and is completely covered with hair. After this time it 
grows very rapidly and may be seen moving around by 
watching the flank closely. The mare carries her foal 
eleven months, but in some cases an aged mare has been 
known to carry her foal over twelve months. In rare 
cases young mares may lack a few days of eleven months. 

The Average Periods of Gestation of Domestic 
Animals. 

Mare 11 months Goat 5 months 

Ass 12 months Sow syo months 

Cow 9 months Bitch 9 weeks 

Sheep 5 months Cat 8 weeks 

Note — A mare having been served by a stallion may 
occasionally in the course of four or five weeks, manifest 
a desire for a second visit from the male ; is again served 
and conceives both times. This is known as superfoeta- 
tion. Such a case has been recorded by a veterinarian; 
the animal in question, a mare, giving birth to a horse 
colt and a mule colt, both dead. The mare had been 
covered by a jack and subsequently by a horse. 

Signs of Pregnancy. — The veterinarian is occasion- 
ally called upon to give an opinion as to the pregnancy 
or non-pregnancy, of an animal and consequently should 
familiarize himself with the various indications which 
tend to prove the absence, or presence, of this condition. 
As a rule, when the mare conceives, heat, or the desire 
for the male, is no longer observable, and, on being led 
to the horse, she not only refuses to receive his caresses, 
but assumes the offensive, viciously striking and biting 
at him until led away. Soon the hair becomes more 



EMBRYOLOGY 83 

glossy, and the mare becomes quieter in disposition. This 
change is usually well marked in mares that are of a 
vicious disposition. The abdomen gradually enlarges as 
pregnancy advances, the right side being a little larger 
than the left. This enlargement is especially well marked 
in the cow. In some cases the beating of the foetal heart 
may be heard with the assistance of the stethoscope. Such 
an examination is, however, very likely to give rise to 
mistakes. After the eighth month well-marked symp- 
toms of pregnancy are manifested, the belly at this time 
being considerably distended, the back sinking, etc. Be- 
fore this time it is, however, impossible to make a positive 
statement as to the condition of the animal except by 
making a very close and thorough examination per rec- 
tum. The rectum should be cleared out by means of an 
enema '(injection) of tepid water; the hand and arm 
should be well oiled and passed into the rectum. The 
region of the uterus being reached, an examination may 
be made of its condition. As the time for parturition ap- 
proaches, the ligaments relax to a greater or less degree, 
and a well-marked depression or sinking in the lumlo- 
sacral region may be observed, the udder or bag enlarges, 
and milk is secreted. The secretion of milk sometimes 
appears long before the time of parturition, and has fre- 
quently been noticed to take place in animals that have 
never been bred. As a rule the animal shows slight un- 
easiness for a day or two before parturition, slight ab- 
dominal pain, etc., being manifested. About this time 
the vulva becomes larger, and presents more or less tume- 
faction. There may also be observed a flow of mucous 
taking place from the vulva for a day or two before par- 
turition. 



INDEX 



HORSE 

Descriptive Anatomy 5 

Dessection 6 



BONES 
Osteology 

Back Bones 11 

Breast Bone 12 

Cannon Bone 13 

Carpus 13 

Cervical Vertebrae 11 

Classes of Bones 9 

Coccygeal Vertebrae 12 

Coffin Bone 14 

Contents of Bones 9 

Distal Phalanx 14 

Dorsal Vertebrae 11 

Femur 15 

Fibula 16 

Fore-arm Bone (large) 13 

Fore-arm Bone (small) 13 

Hip Bones 13 

Hock Bones 16 

Humerus 12 

Knee 13 

Loin Bones 11 

Lumbar Vertebrae 11 

Median Phalanx 14 

Metacarpal 13 

Metatarsus 17 

Neck Bones 11 

Os Coronae 14 

Os Metacarpi Magnus 13 

Os Metatarsi Magnum 17 

Os Naviculare 15 

Os Pedis 14 

Os Suffraginis 14 

Ossa Metatarsi Parva 17 

Ossa Metacarpi Parva 14 

Pastern Bone (large) 14 

Pastern Bone (small) 14 

Patella 15 

Pelvic Bones 12 

Proximal Phalanx 14 

Radius 13 

Ribs 12 

Rump Bones 12 

Sacral Vertebrae 12 

Scapula 13 

Sesamoid Bones 14 

Shoulder Blade 13 



Shoulder Bone 12 

Shuttle Bone 15 

Skeleton 7 

Skull 10 

Splint Bones (fore limb) 14 

Splint Bones (hind limb) 17 

Sternum 12 

Stifle Bone 15 

Structure of Bones 8 

Tail Bones 12 

Tarsus 16 

Thigh Bone 15 

Tibia 16 

Ulna 13 

JOINTS 

ARTHROLOGY 

Adipose Tissue 22 

Cartilage 21 

Connective Tissue 21 

Elastic Tissue (Yellow) 22 

Fat 22 

Ligaments 22 

Synovial Membranes 23 

Synovia 23 

Joints 

Carpus 25 

Classes of Joints 24 

Coffin Joint 26 

Elbow Joint 24 

Fetlock Joint 25 

Hip Joint 26 

Hock Joint 26 

Joints of the Front Leg 24 

Joints of the Hind Leg 26 

Knee Joint 25 

Motion in Joints 24 

Pastern Joint 25 

Shoulder Joint 24 

Stifle Joint 26 

Tarsus 26 

MYOLOGY 

Abdominal Muscles 32 

Back Muscles 30 

Coccygeal Muscles 30 

Deep Layer of Muscles 31 

Gluteal Muscles 30 

Gullet Muscles 30 



Head Muscles 30 

Hip Muscles 30 

Involuntary Muscles 35 

Leg Muscles (front) 33 

Leg Muscles (hind) 34 

Muscles 28 

Neck Muscles 30 

Pharynx Muscles 30 

Shoulder Muscles 32 

Superficial Layer of Muscles. 29 

Tail Muscles 30 

Voluntary Muscles 30 

SPLANCHNOLOGY 

Air Cells 53 

Bladder 56 

Bowels 41 

Breathing, Normal 55 

Bronchial Tubes 53 

Canine Teeth 49 

Cementum (or crusta petrosa).48 

Dentine (or ivory) 48 

Digestive Apparatus 37 

Enamel 48 

Fallopian Tubes 62 

Female Genital Organs 62 

Generative 58 

Incisor Teeth 49 

Kidneys 56 

Larynx 53 

Liver 43 

Lungs 54 

Male 58 

Mammary Glands 65 

Molar Teeth 49 

Nasal Chambers 52 

Nostrils 52 

Organs of Respiration 52 

Ovaries 62 

Pancreas 43 

Penis 61 

Permanent Teeth 49 

Rectum 42 

Respiration 54-55 

Respiratory System of the 

Horse 52 

Salivary Glands 39 

Scrotum 58 

Semen 61 

Sheath 61 

Spleen 43 

Sperm 61 

Spermatic Cords 60 

Stomach 40 

Teeth 48 

Teeth Tables (comparative) .51 

Temporary Teeth 49 

Testicles 59 



Ureters 56 

Urethra 57 

Urinary System ....56 

Uterus 62 

Vagina 64 

Vas Deferens 60 

Vesiculae Seminales 60 

Vulva 64 

Windpipe or Trachea 53 

Wolf Teeth 49 

Womb 62 

ANGILOGY 

Arteries 70 

Blood 67 

Blood-vascular System 67 

Capillaries 71 

Circulation 69 

Corpulscles 67 

Course of Blood 71 

Heart 68 

Liquor Sanguinis 68 

Lymphatic System 73 

Veins 71 

NEUROLOGY 

Brain 73 

Spinal Cord 73 

AESTHESIOLOGY 

Anatomy of the Foot 78 

Dermis 77 

Ear 75 

Epidermis 77 

Eye 75 

Foot Sole 80 

Foot Frog 80 

Foot Wall 79 

Frog of Foot 80 

Hair 77 

Skin 76 

Sole of Foot 80 

Wall of Foot 79 

EMBRYOLOGY 

Development of Young .81 

Gestation of Domestic Ani- 
mals 83 

Pregnancy 83 

COMPARATIVE ANATOMY 

Abomasum 46 

Air Cells 53 

Aves 30 



Back Bones 18 

Bowels 4G 

Bronchial Tubes 53 

Carnivora 19 

Cervical 18 

Chewing Cud 46 

Coccygeal 18 

Comparative Osteology ....17 

Cud Chewing 46 

Digestive System 44 

Dorsal 18 

Forth Stomach 46 

Genital Organs of the Bull... 65 
Genital Organs of the Cow... 66 

Gullet 44 

Hip Bones 19 

Honey Comb 45 

Larynx 53 

Liver 46 

Loin Bones 18 

Lumbar 18 

Lungs 54 

Mammary Glands 66 

Many Plies 45 

Neck Bones 18 

Normal Breathing 55 

Nostrils 55 

Oesophagus 44 

Omasum 45 

Omnivora 19 

Paunch 45 

Pelvis Bones 19 



Penis 65 

Process of Digestion 47 

Respi'rations per Minute of 

Different Animals 54 

Respiratory System of the Ox. 55 

Reticulum 45 

Rumen 45 

Ruminantia 44 

Ruminantia (cud chewing an- 
imals) 18 

Rumination 47 

Rump Bones 18 

Sacrum 18 

Salivary 44 

Sheath 65 

Skull 13 

Spermatic Cord 65 

Stomach 45 

Tail Bones 18 

Teeth 44 

Teeth, Front 44 

Teeth, Molars 44 

Testicles 65 

Thoracic Cavity (lung cavity) . 55 

Tongue 44 

Trachea 53 

Urethra 66 

Uterus 66 

Urinary System of the Ox... 58 

Vertebrae 18 

Windpipe 53 

Womb 66 



Press of 
Sweeney, Varney & Straub 
Portland, Oregon 



LIBRARY OF congress; 

■liillll 

002 829 1'5""™'^ 



